2023/5, стр. 532 - 546

EDUCATIONAL POLICY, SPECIALISED STAFF, INNOVATIONS AND RECREATIONAL INDUSTRY

Резюме:

Ключови думи:

1. Introduction

Wellness tourism refers to travel that prioritizes health and well-being, with the goal of enhancing physical, mental, and spiritual health. It typically involves activities such as spa treatments, fitness classes, meditation, and healthy eating (Trendafilov 2013; Chipeva 2019; Nesheva, 2019; Ignatova et al. 2020). Recreational programs, on the other hand, are leisure activities that promote physical and mental relaxation, such as hiking, camping, and sports (Chipeva 2019, pp. 51 – 53; Ignatova 2022). As we mentioned, in other publications, wellness tourism is a growing industry, and it presents an opportunity for Bulgaria to attract more visitors and generate revenue (Polimenov 2018; Tsanov 2015, pp. 17 – 26 ;Dimitrova, Izov et al. 2021). However, the lack of clear definitions and standards in the industry, as well as the shortage of specialized personnel, can hinder its growth and competitiveness (Dimitrova et al. 2018; Polimenov 2019).

To address these challenges, Bulgaria may need to invest in training programs for wellness and recreational professionals and create clear guidelines and standards for the industry. Additionally, efforts to improve health literacy among Bulgarians can increase demand for wellness tourism domestically and help to establish Bulgaria as a destination for international travelers seeking wellness experiences.

The development of polyvalent Wellness & Spa culture is very important (Ignatova 2022). The significance of physical activity in the aquatic environment must be acknowledged for its positive impact on customer health and quality of life (Nesheva 2016; Chipeva 2020; Ignatova et al. 2020). Finding highly qualified personnel for wellness centers is a major problem, and the situation is not improving (Polimenov 2022). The industry is facing a "War for Talents," and many owners of wellness centers report difficulty finding the right mix of experience and skills in their employees. The demand for specialised packages is growing rapidly, requiring more staff than what is currently available. This has led to an increased focus on education, training, and certification programs for employees in the industry. The global wellness tourism market is valued at 425 billion euros, with 36% generated by Europe, and six of the top 10 destinations are located in Europe. The European Wellness industry recognises the importance of training and education to maintain its leading position and ensure high-quality services (Trendafilov at al 2013). After the Global pandemic situation, promoting public health can be achieved through connected educational, social, and health policies, as well as standards and restrictions (Nesheva 2020; Tomova 2021). The global COVID-19 pandemic has shown us the importance of crisis management on a worldwide scale (Ilinova et al. 2019; Ignatov et al. 2021). To restore the happiness of society, it's crucial to enhance individual life capacities and enhance the social environment (Dimitrova et al. 2021). The thermal tourism on the Balkans, and specificly in Bulgaria has an old and rich history. According published analysis, Bulgarian traditions are based on more than 800 mineral springs with different temperatures, physical properties and chemical composition (Trendafilov et al. 2013). At the moment, the Recreational Industry and Niche Tourism (Wellness, SPA, Thalasso) sectors still lack a clear vision, concept, regulated requirements and/or standards (Doncheva et al. 2016; Dimitrova et al. 2018). There is a lack of personnel trained through specialised programs, who have acquired specific knowledge and skills for successful implementation and achieving high quality of services, with command of at least 2 foreign languages (Dimitrova 2020).

2. Methods

Purpose: The aim of this study was to evaluate the demand for specialised personnel in the recreational industry and to design innovative educational tools for certification in Wellness & SPA & Thalasso culture.

Focus: Our scientific interests was focused on developing content for two new educational tools, one for instructors and sub-instructors in Wellness and Thalasso culture, and the other for two educational levels: “Bachelor” and master and PhD – as the head of a Wellness / SPA / Thalasso Center.

Subject: The study was conducted among 110 specialists in Thalasso culture and 120 specialists in Wellness & Spa culture. The subjects were mostly Bulgarian, with an average age of 35 years and a balanced equity of both gender. They were distributed into tree different groups (22 – 32 years; 33 – 42 years; 43 – 56 years), by their background in practice, and job position rank.

Expertise and funding: The study was carried out to examinates the recreational industry needs for specialised staff, by the scientific team of the National Sports Academy "V. Levski". All experts was selected by public announcement under to complete the goals of the first Bulgarian centre of Excellence Heritage BG1. This University is recognised for its educational standards and scientific expertise in Wellness & SPA & Thalasso culture, having received accreditation with an excellent score from NAOA2. The study participants, consisting of both working and learning personnel in the field, gave their consent for the publication of their data. The study was conducted from June 2018 to June 2022 and involved administering a psychometric test to gauge the opinions of the respondents (during the pandemy our work was online).

Procedures: The data was collected through an adapted version of specialised and standardised survey forms using Google Drive (tools). The research utilised a psychometric assessment test to achieve its set goal. The test tool was used to gather information from individuals working and learning in specialised fields in the Bulgarian Niche tourism industry. The results were analysed to determine the relative importance of various indicators for the quality of training programs and the Thalasso instructor profession. The questions were ordered based on their relevance to create a ranking scale, which reflects the quantity of properties associated with each question. This ranking scale allows for an evaluation of the relative significance of each studied property in regards to the quality of services and centers in Bulgarian Niche tourism. The survey also explored the desired content and design of a smart app that is being developed to support personnel in this industry. This app will serve as a certification tool and improve the quality of services in the recreational sector.

3. Results

The “Heritage BG” initiative has achieved remarkable progress by introducing innovative developments. It puts forward a rigorous methodology to tackle the latest European and Bulgarian policies concerning social welfare, education, and tourism. This is achieved by designing new educational programs that cater to diverse job roles and skill sets. Enhancing the nation's well-being index and promoting healthy lifestyles requires the development of innovative methods, treatments, interventions, and extensive research to determine their efficacy. Implementing specialised therapy requires personnel with professional competencies, necessitating the creation of new educational programs for their certification.

The global shortage of skilled workers is a pressing issue (Ellis 2013, pp. 9 – 10). According to data from the GWI, there is a lack of approximately 280,000 individuals with specific knowledge and skills in niche tourism (GWI 2021). The data provided in table 1 represent the actual status of all training programs in the world (2021). This information is published by the GWI research team in the Annual Wellness economy Report. The research also emphasises the importance of specialised programs at various educational levels to train personnel for different positions in the Wellness, SPA, and Thalasso industry, from operational to managerial. This industry, enjoyed by over 4 billion people worldwide, has an annual revenue of around €300 billion (Global Wellness Institute 2023; Polimenov 2014). However, there is a lack of data on the income of the leisure industry in the Balkans (Dimitrova 2018). The Wellness and SPAindustry globally is in need of innovative marketing strategies and management techniques.

A modern theory of the recreational industry and niche tourism that incorporates digitalisation and intelligent services is also necessary (Tsanov 2015; Sachs 2015). According to the Global Wellness Institute (January 2023), regression analysis on a per capita basis calculates the average value of a specific statistic per person in a population, which is used to compare the distribution of a statistic like health, education, and science among different populations, or to analyse changes in a population over time. The relationship between wellness sector spending per capita and happiness is strong and positive at the country level, as shown by regression analyses. A positive correlation between spending and happiness suggests that as people spend more money, their reported levels of happiness increase.

The Cantril ladder is a widely used measure of subjective well-being, which asks individuals to rate their overall life satisfaction on a scale of 0 to 10. However, it is important to note that correlation does not necessarily imply causation. While spending more money may be associated with increased happiness, there could be other factors at play that are contributing to this relationship. The Figure 1 illustrates the Bulgarian educational model that has been implemented in the Recreational Industry and Niche Tourism, and displays the variety of accredited educational and training programs provided by the National Sports Academy “V. Levski.” The delivery of continuing education in the wellness industry presents new challenges,

as it is a fragmented and untested model. Issues related to the management of wellness businesses, as outlined by Ellis (2013), include the difficulty of acquiring the necessary skills and knowledge to take on a management role, as well as the lack of clear criteria for educational and professional competencies in the field. This results in staff having partial knowledge in specific areas rather than a comprehensive understanding of the industry. Additionally, the specific individual wellness sectors that were found to have a positive correlation between spending and happiness may vary, and it is important to consider the nuances of each sector and the specific measures used to assess spending and happiness. As the leading provider of Wellness education in the Balkans, Bulgaria offers 6 accredited programs ranging from a Bachelor's to Doctoral level in Sport and Healthcare. Bulgaria has emerged as a European lider in the niche tourism sector, thanks to its effective implementation of dedicated healthcare and sports programs. It is also the initial nation to offer a comprehensive educational vertical, spanning from secondary/ professional education up to doctoral level, solely for the Recreational Industry and Niche Tourism. The “Heritage BG” project, which is co-funded by the European Structural and Investment Funds, has received recognition and its development and construction are underway, with the aim of establishing a center of excellence for the creative and recreational industries. Additionally, a Center for Scientific Excellence is also being built, providing the highest level of scientific infrastructure in Europe. The new staff's social objective is to promote wellness and spa culture through student volunteers from the “Vasil Levski” NSA in “Wellness & SPA & Thalasso Culture” and the young specialists network of “Sin Cluster” and “Cluster Bridge.” The Bulgarian events under the UN campaign spread awareness about the importance of water in a healthy lifestyle and the responsible use of mineral and spring water resources. Those international forums arranged to advocate for a culture of health and encourage disease prevention practices through social, educational, and scientific innovations. These endeavors will enable Bulgaria to evolve into a knowledge-driven economy and a “water-based Silicon Valley.”

Moreover, an advanced scientific infrastructure is being established in Sofia to push forward the emerging field of "Aquaphotomics," a global innovation pioneered by Bulgarian Professor Rumyana Tsenkova. For the first time in the country, novel scientific advancements, standards, and innovative business products are being formulated and put into operation, leading to the establishment of new policies and strategies in the domain.

The findings from the survey in Bulgaria highlight 6 crucial indicators for evaluating Wellness facilities and 6 for customer expectations of Wellness staff, which were prioritised based on their significance. The results of a psychometric experiment, shown in table 3, highlight the key indicators in determining the quality and competitiveness of Wellness centers, ranked in order of importance and significance. After analysing the data, it can be deduced that the top two positions (first place weight: 553, 86% units; second 473, 65,5%) are determined by the expertise of the personnel and the efficiency of service provision. Third and fourth on the list are “The center must have state-of-the-art facilities and equipment” (Weight: 366 units – 69%) and “The center must have a well-developed investment plan for wellness & spa business development” (Weight: 261 units – 41.5%). The indicators “The center must have a strong governance structure and management proceduresˮ and "The center must have a positive image and competitivenessˮ received weights of (Weight: 209 units – 71.5%) and (Weight: 197 units – 54.5%) respectively.

The Wellness Institute Bulgaria (our scientific partner) has listed various factors from 7th to 10th place, including a diverse array of Wellness services, a well-planned pricing strategy, adaptable marketing policies, favorable working conditions and employee advancement opportunities. However, for this study, only the first 6 indicators are taken into consideration by the Consortium. The results of the survey, which identified priority indicators, are being utilised to unify standards for all stakeholders and politicians responsible for classifying Wellness & Spa establishments and certifying personnel in the Wellness industry (in accordance with the criteria system harmonised by the EU). The survey revealed a pressing need for training programs for future professionals in the wellness sector (with focus in Niche tourism). These professionals require a solid foundation of knowledge and skills in both organisational and methodological areas, as well as a high level of motivation to deliver quality services that meet the needs of wellness customers. It is necessary to establish connections between academic institutions, VET centers, secondary schools, and professional educational bodies, creating a bridge between theory and practical experience in the wellness business and industry. The Erasmus+ project, which has produced innovative Wellness training and certification programs, contribute to inclusive, smart growth in the EU through its educational and labor policies. The CoE “Heritage BGˮ strives to cultivate consciousness and advocate for a culture of excellence in the R&D field of youth and the utilisation of water for health preservation and therapy. In collaboration with media groups, organisations, civil society, businesses, industry, local and governmental authorities, educational institutions, and notable figures, we have initiated a comprehensive information drive at the national, regional and international levels, reaching out to over 13,000 individuals. This initiative is linked to the UN's worldwide “Water Dayˮ campaign and introduces the innovative global notion of “Wellness for all.ˮ Figure 3 illustrates the steps and logistics involved in Bulgarian scientific innovation and research business models aimed at creating an optimal environment for implementing a knowledgebased economy.

This information is based on official accreditation documentation and has been designed to reflect the changing needs of the specialised personnel in this field. The process of upgrading the education system takes into account best European practices, market research, and the needs of the recreational industry and niche tourism. To achieve the realisation of accomplished and upcoming Bulgarian scientific innovations and research business models, several logistics need to be considered. Key logistics include:

1. Funding: Adequate funding is essential to realize Bulgarian scientific innovations and research business models. Private investors and the Bulgarian government should invest in these projects to ensure sufficient resources to support research and development processes.

2. Collaboration: Collaborations between researchers, academics, and business professionals are vital to realize Bulgarian scientific innovations and research

business models. They can share ideas, expertise, and resources, leading to more innovative and effective solutions.

3. Intellectual Property Rights: Clear and well-defined intellectual property rights are essential to protect Bulgarian scientists' ideas, inventions, and innovations. The Bulgarian government should update intellectual property laws and make it easy for innovators to register and protect their intellectual property.

4. Marketing and Commercialization: Successful realization of Bulgarian scientific innovations and research business models depends on effective marketing and commercialization. The Bulgarian government should support the development of marketing and commercialization strategies to help innovators promote their products and services effectively.

5. Infrastructure: Adequate infrastructure, including laboratories, research facilities, and technological infrastructure, is crucial for Bulgarian scientific innovations and research business models. The Bulgarian government should invest in infrastructure to support research and development and ensure that facilities are up-to-date and well-equipped.

6. Talent Development: Developing the talent pool of scientists, engineers, and other professionals is crucial to realize Bulgarian scientific innovations and research business models. The Bulgarian government should invest in training and education opportunities, encourage young people to pursue science and engineering careers, and create opportunities for researchers to collaborate with industry professionals.

4. Discussion

Realising Bulgarian scientific innovations and research business models in Niche tourism requires efforts from the Bulgarian government (Torism Ministry), private investors (Resorts, hotels and restaurants), and the scientific community (Centre of Excellence). By investing in funding, collaboration, intellectual property rights, marketing and commercialization, infrastructure, and talent development, Bulgaria can create an environment that fosters innovation and supports the realization of scientific innovations and research business models. The new job position of Wellness and of Thalasso Instructor is the result of a cross-border collaboration among vocational education and training (VET) providers and businesses in the wellness tourism sector, as part of the Erasmus+ KA2 WELVET project and OP ONIR. The project's main objective is to address the scarcity of proficient personnel in the European wellness and of Thalasso tourism sector, by introducing a VET course for the emerging occupation of “New jobs.ˮ It is imperative to develop educational curricula and levels for wellness in both secondary schools and higher education (bachelor, master and PhD degree). This new role will enable educational providers to offer continuous education and training to professionals, who already possess a vocational qualification in the Tourism and Hospitality field. This will help bridge the existing gap in the shortage of qualified staff to serve as Wellness and as Thalasso Instructors in Niche Tourism, as this occupations has yet to be standardised at the secondary education level and accredited on higer level, in many nations. In addition, the project also has a specific goal of ensuring continuous training by adding supplementary units to existing qualifications and levels, thereby enhancing employability and aligning with the current needs of the tourism and hospitality sector. Moreover, the innovative delivery method of a Smart mobile app is designed, tested, and produced to provide free and easily accessible training in the digital form. The development of the Wellness and the Thalasso Instructor occupation is part of the initiative to promote transnational cooperation between educational providers and economic actors in the Wellness & Spa & Tjalasso tourism field. This educational instrument is to address the scarcity of trained personnel in the European wellness tourism industry by creating a VET course for the emerging occupation of “Wellness and Thalasso Instructor”. In addition we ensuring continuous training by adding supplementary units to existing qualifications and levels. Thereby enhancing employability and aligning with the current needs of the tourism and hospitality sector. Moreover, the innovative delivery method of a Smart mobile app was developed and tested. The study covers four main regions of the EU (South-Eastern, Central, North, and Western Europe) and also emphasises the dissemination and exploitation of its results. The learning app is available for free in five languages (English, Bulgarian, Estonian, Macedonian, and German). Bulgaria is increasingly exploring alternative forms of Niche tourism to attract more global clients and promote sustainable development in rural regions. However, one major challenge is to ensure that clients receive appropriate guidance and follow-up from well-trained staff. Bulgaria aims to become a leading global provider of wellness products, but the country needs to address the current shortage of skilled staff in the sector to maintain quality in the face of increasing global competition..

5. Conclusions

To summarise, based on the survey findings, stay clear that collaboration between professional associations, NGOs, and the government is necessary for the growth and regulation of Niche tourism in Bulgaria. Specifically, action is needed to:

1. Establish standards for categorising Wellness and SPAs and implement procedures for evaluating their quality services and staff;

2. It is important to implement personnel qualification requirements in Niche tourism, especially in Bulgaria, as the country has the potential to become a European leader in this field with its seven specific educational programs. By setting standards for personnel qualifications, Bulgaria can ensure that the staff providing services in the Niche tourism industry are well-trained and knowledgeable in their respective fields, thus enhancing the quality of services provided to clients. This can also contribute to the country's overall competitiveness in the global tourism market and support its goal of sustainable development in rural regions.

3. Enhance the competitiveness of SPAs in both the domestic and international markets by offering a wider range of activities and services, implementing a balanced pricing policy, investing in projects, promoting packages, and determining strategic development plans.

Acknowledgments & Funding

The analysis was financially supported by project BG05M2ОP001-1.001-0001 Building and developing a Centre оf Excellence “Heritage BG”, funded by the Оperatiоnal Program “Science and Education for Smart Growth”, priority axis 1 “Research and technological development”.

Declarations of informed consent have been obtained for the publication of the surveyed data.

NOTES

1. Project BG05M2OP001-1.001-0001 “Construction and development of the Center for Excellence “Heritage BG” under the Operational Program “Science and Education for Smart Growth”, priority axis 1 “Research and technological development”, Procedure BG05M2OP001-1.001 "Construction and Development of centers of excellence', Component 4 “New technologies in the creative and recreational industries”.

2. NAOA: National Agency for information and documentation in Sofia, Bulgaria.

REFERENCES

CHIPEVA, M., 2019. Kango dshŭmps Aerobika. Sofia: Avangard Prima. ISBN 978-619-239-131-7. [In Bulgarian].

DIMITRОVA, B.; PОLОMENОV, М.; TRENEVA, V.; NESHEVA, I.; IVANОVA, V.; TRENDAFILОV, D., 2018. Sоtsialna snachimоst na uelnes (wellness) kulturata: sravnitelen analis pо danni оt nauchni issledvania na Galap interneshanal. Sоfia: Avangard. ISBN 978-619-160-989-5. [In Bulgarian].

DIMITRОVA, B.; IZОV, N.; ALEXANDRОVA, V.; IОSIFОV, R.; IGNATОVA, D.; TRENDAFILОV, D.; PETRОV, V.; VASILEVA, G., 2021. Smart kоgnitiven instrumentation. Vŭnshna оtsenka na prоfesiоnalni kоmpetentsii sa kadri v Nishоv turisŭm. Sоfia: NSA Pres. ISBN: 978-954-718-675-0. [In Bulgarian].

DONCHEVA, L. & DIMITROVA, L., 2016. Innovative Way of Teaching English in Class and Its Influence on Pupils’ Level of Concentration. Paper presented at the Vth Congreso de Internacional de Competencias B†sicas, 13 – 15 de Abril 2016: la competencia en comunicaci–n lingü‘stica, pp. 21 – 22, Ciudad Real.

ELLIS, S., 2013. The global wellness tourism economy Report. Global Wellness Tourism Congress (Delhi, India). Global wellness institute, Miami, USA.

GLOBAL WELLNESS INSTITUTE, 2014. Economic Report, Miami, USA. Available at: https://www.globalwellnessinstitute.org/. (Accessed 2017, Dec.).

HARISANOVA, O., 2022. New scientific infrastructure for innovations on the creative and recreative industries. Smart innovations in the Recreative & Wellness Industry and Niche Tourism Journal, vol. 4, no. 1 – 2, pp. 17 – 21.

IGNATОVA, D., ILIEV, A., 2020. Mоtоr qualities and their influence оn the children’s development. Smart Innоvatiоns in Recreatiоnal, Wellness Industry and Niche Tоurism, vol. 2, no. 1 – 2, pp. 16 – 44. ISSN: 26034921 (оnline). Available at: https://scjоurnal. glоbalwaterhealth.оrg/.

IGNATOVA, D. & A. ILIEV, 2022. Benchmarking for the development of speed and power characteristics. Strategies for Policy in Science and Education-Strategii na Obrazovatelnata i Nauchnata Politika, vol. 30, no. 4, pp. 411 – 421. DOI: 10.53656/str2022-4-6-ben.

IGNATOVA, D., 2022. Reliable Instruments in the Assessment of Schoolar Wellness in the Primary Educational Level. Strategies for Policy in Science and Education-Strategii na Obrazovatelnata i Nauchnata Politika, vol. 30, no. 1, pp. 70 – 81. DOI:10.53656/ str2022-1-4-rel. [In Bulgarian].

IGNATОV. I.; ANGELCHEVA, M. & ANGUSHEV, I., 2021. Dоses оf Са2+, Mg2+, K+, Nа+, Mn2+ and Sn2+ in Mоuntain Spring and Mineral Waters in Hydratiоn Reactiоn During Spоrt Training and Recоvery; Cоmbinatiоn with Vitamins. Jоurnal оf Pharmaceutical Research Internatiоnal, vol. 33. No. 16, pp. 76 – 85. https://www.jоurnaljpri. cоm/index.php/JPRI /article/view/31299, Article nо. JPRI.66181 ISSN: 2456-911 (Past name: British Jоurnal оf Pharmaceutical Research, Past ISSN: 2231-2919, NLM ID: 101631759).

ILINОVA, B. & TОTEVA, M., 2019. Pregnancy and delivery оf elite cоmpetitive athletes. Internatiоnal Scientific Cоngress-Applied Spоrts Sciences, Proceeding Bооk, pp. 280 – 285, NSA 2019. eISBN: 978-954718-601-9. Available at: www.icass.

NESHEVA, I., 2016. Research impact through scientific reports in international forum. Summary case Studies. Sofia: Avangard Prima.

NESHEVA, I., 2020. Information system for inclusion of women with normal pregnancy in gymnastics program. Smart Innovations on the Recreative & Wellness Industries and Niche tourism, vol. 2, no. 1, pp. 33 – 39. eISSN: 2603-4921. Available at: https://scjournal. globalwaterhealth. org/.

POLIMENOV, M., 2019. Transfer of innovation in the service technology for increasing the restaurant quality product. Smart Innovations in Recreational, Wellness Industry and Niche Tourism, vol. 1, no. 2, pp. 29 – 35, ISSN 2603-4921 (online). Available at: https://scjournal. globalwaterhealth.org/.

POLIMENOV, M., 2022. Tourism Education Policies, Competencies and Development Incentives. Strategies for Policy in Science and EducationStrategii na Obrazovatelnata i Nauchnata Politika, vol. 30, no. 3, pp. 133 – 145. [In Bulgarian]. DOI: 10.53656/str2022-3-7-tou.

SACHS, J., 2015. Sustainable Development Goals (SDGs). Sustainable development is a holistic approach to well-being. Paper presented to heads of state at a special summit at the United Nations, in September 2015. The 70th anniversary of the UN. New York. Available at: www. globalwellnessinstitute.com.

TRENDAFILОV, D. & DIMITRОVA, B., 2013. Aqua spinning as antistress health preventiоn. Spоrt Mоnt, XI (37-38-39), pp. 454 – 460.

TOMOVA, T., 2021. Menstrualni narusheniya – rasprostranenie i proyavlenie. Smart Innovations in Recreational, Wellness Industry and Niche Tourism, vol. 3, no. 2, pp. 33 – 38. еISSN 2603-493X (online). Available at: https://scjournalbg. globalwaterhealth.org//.[In Bulgarian].

TSANOV, I., 2015. Ikonomika na sporta. Monografiya. Sofia: BAK. [In Bulgarian].

VESELINOV, D., 2021. Dialogat v obrazovanieto. VESELINOV, D., et al. (Eds). Deseti mezhdunaroden esenen nauchno-obrazovatelen forum Dialogat v obrazovanieto – suvremennost i perspektivi, pp. 11 – 16. Sofia: Sofia University. ISBN 978-954-07-5231-0. [in Bulgatian].

Internet sources:

Centers for Excellence and centers for competences. Available at:: https:// naukamon.eu/centrove-nauka/

Ministerstvoto na obrasovanieto i naukata. 2021. Vse po-malko shte savŭrshvat visshe obrasovanie do 2025g. [In Bulgаriаn]. Available at: https://web.mon.bg/bg/news/4266.

Natsionalniya statisticheski institut oktomvri 2021g. [In Bulgаriаn & English]. Available at: https://nsi.bg/sites/default/files/files/publications/ God2021.pdf.

WHO, World Health organisation. Available at: https://www.un.org/en/ isotope-articles/10610