Não informado. (2020). Progress Report of the Bulgarian National Committee for the International Biological Programme. Bulgarian National Committee for the International Biological Programme.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Progress Report of the Bulgarian National Committee for the International Biological Programme. Sofia: Bulgarian National Committee for the International Biological Programme, 2020.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Progress Report of the Bulgarian National Committee for the International Biological Programme. Bulgarian National Committee for the International Biological Programme, 2020.
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