Roberts, Benjamin W.; Thornton, Christopher P. (2009). „Development of metallurgy in Eurasia”. Antiquity. Department of Prehistory and Europe, British Museum. 83 (322): 1015. doi:10.1017/S0003598X00099312. Приступљено 28. 7. 2018. „In contrast, the earliest exploitation and working of gold occurs in the Balkans during the mid-fifth millennium BC, several centuries after the earliest known copper smelting. This is demonstrated most spectacularly in the various objects adorning the burials at Varna, Bulgaria (Renfrew 1986; Highamet al. 2007). In contrast, the earliest gold objects found in Southwest Asia date only to the beginning of the fourth millennium BC as at Nahal Qanah in Israel (Golden 2009), suggesting that gold exploitation may have been a Southeast European invention, albeit a short-lived one.”
Schoenberger, Erica (2015). Nature, Choice and Social Power. Routledge. стр. 81. ISBN978-0-415-83386-8. „The graves at Varna range from poor to richly endowed, suggesting a rather high degree of social differentiation. Their discovery has led to a re-evaluation of the form of social organization characteristic of the Varna culture and of the onset of social stratification in Neolithic cultures.”
Bell, John D. „Bulgaria – Late Communist rule”. Encyclopædia Britannica. Приступљено 28. 7. 2018. „Bulgaria gave the highest priority to scientific and technological advancement and the development of trade skills appropriate to an industrial state. In 1948 approximately 80 percent of the population drew their living from the soil, but by 1988 less than one-fifth of the labour force was engaged in agriculture, with the rest concentrated in industry and the service sector.”
Denizova, Vera (23. 10. 2017). Бюджет 2018: Повече за заплати, здраве и пенсии [2018 Budget: More for salaries, health and pensions] (на језику: бугарски). Kapital Daily. Приступљено 16. 7. 2018.CS1 одржавање: Формат датума (веза)
„Bulgaria Factbook”. United States Central Command. децембар 2011. Архивирано из оригинала 18. 10. 2011. г. Приступљено 4. 10. 2018.CS1 одржавање: Формат датума (веза)
„The Gumelnita Culture”. Government of France. Архивирано из оригинала 13. 10. 2012. г. Приступљено 4. 12. 2011. „The Necropolis at Varna is an important site in understanding this culture.”CS1 одржавање: Формат датума (веза)
Tillier, Anne-Marie; Sirakov, Nikolay; Guadelli, Aleta; Fernandez, Philippe; Sirakova, Svoboda (октобар 2017). „Evidence of Neanderthals in the Balkans: The infant radius from Kozarnika Cave (Bulgaria)”. Journal of Human Evolution. 111 (111): 54—62. ISSN0047-2484. PMID28874274. doi:10.1016/j.jhevol.2017.06.002.CS1 одржавање: Формат датума (веза)
„A 14C chronology for the Middle to Upper Palaeolithic transition at Bacho Kiro Cave, Bulgaria”. Nature Ecology & Evolution. 4 (6): 794—801. 2020. PMID32393865. doi:10.1038/s41559-020-1136-3.
Roberts, Benjamin W.; Thornton, Christopher P. (2009). „Development of metallurgy in Eurasia”. Antiquity. Department of Prehistory and Europe, British Museum. 83 (322): 1015. doi:10.1017/S0003598X00099312. Приступљено 28. 7. 2018. „In contrast, the earliest exploitation and working of gold occurs in the Balkans during the mid-fifth millennium BC, several centuries after the earliest known copper smelting. This is demonstrated most spectacularly in the various objects adorning the burials at Varna, Bulgaria (Renfrew 1986; Highamet al. 2007). In contrast, the earliest gold objects found in Southwest Asia date only to the beginning of the fourth millennium BC as at Nahal Qanah in Israel (Golden 2009), suggesting that gold exploitation may have been a Southeast European invention, albeit a short-lived one.”
Hope, Kerin (11. 1. 2018). „Bulgaria battles to stop its brain drain”. The Financial Times. Архивирано из оригинала 10. 12. 2022. г. Приступљено 7. 9. 2018. „But a sharp decline in the quality of state healthcare and high poverty rates—42% of the population are at risk of poverty in old age, according to Eurostat—gives Bulgaria the second-lowest life expectancy in the EU after Lithuania.”
Видово разнообразие на България [Species biodiversity in Bulgaria] (PDF) (на језику: бугарски). UNESCO report. 2013. Архивирано(PDF) из оригинала 2022-10-09. г. Приступљено 30. 7. 2018.
Hope, Kerin (11. 1. 2018). „Bulgaria battles to stop its brain drain”. The Financial Times. Архивирано из оригинала 10. 12. 2022. г. Приступљено 7. 9. 2018. „But a sharp decline in the quality of state healthcare and high poverty rates—42% of the population are at risk of poverty in old age, according to Eurostat—gives Bulgaria the second-lowest life expectancy in the EU after Lithuania.”
Hawkesworth, Ian (2009). „Budgeting in Bulgaria”(PDF). OECD Journal on Budgeting (3/2009): 137. Архивирано из оригинала(PDF) 2022-10-09. г. Приступљено 6. 8. 2018.CS1 одржавање: Формат датума (веза)
Tillier, Anne-Marie; Sirakov, Nikolay; Guadelli, Aleta; Fernandez, Philippe; Sirakova, Svoboda (октобар 2017). „Evidence of Neanderthals in the Balkans: The infant radius from Kozarnika Cave (Bulgaria)”. Journal of Human Evolution. 111 (111): 54—62. ISSN0047-2484. PMID28874274. doi:10.1016/j.jhevol.2017.06.002.CS1 одржавање: Формат датума (веза)
„A 14C chronology for the Middle to Upper Palaeolithic transition at Bacho Kiro Cave, Bulgaria”. Nature Ecology & Evolution. 4 (6): 794—801. 2020. PMID32393865. doi:10.1038/s41559-020-1136-3.
OECD Economic Surveys: Bulgaria. OECD. 1999. стр. 24. ISBN9789264167735. Приступљено 4. 10. 2018. „The previous 1997 Economic Survey of Bulgaria documented how a combination of difficult initial conditions, delays in structural reforms, ... culminated in the economic crisis of 1996–97.”CS1 одржавање: Формат датума (веза)
oecd.org
Hawkesworth, Ian (2009). „Budgeting in Bulgaria”(PDF). OECD Journal on Budgeting (3/2009): 137. Архивирано из оригинала(PDF) 2022-10-09. г. Приступљено 6. 8. 2018.CS1 одржавање: Формат датума (веза)
Видово разнообразие на България [Species biodiversity in Bulgaria] (PDF) (на језику: бугарски). UNESCO report. 2013. Архивирано(PDF) из оригинала 2022-10-09. г. Приступљено 30. 7. 2018.
„The Gumelnita Culture”. Government of France. Архивирано из оригинала 13. 10. 2012. г. Приступљено 4. 12. 2011. „The Necropolis at Varna is an important site in understanding this culture.”CS1 одржавање: Формат датума (веза)
„Bulgaria Factbook”. United States Central Command. децембар 2011. Архивирано из оригинала 18. 10. 2011. г. Приступљено 4. 10. 2018.CS1 одржавање: Формат датума (веза)
