Não informado. (2020). Progress Report of the Bulgarian National Committee for the International Biological Programme. Bulgarian National Committee for the International Biological Programme.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Não informado. Progress Report of the Bulgarian National Committee for the International Biological Programme. Sofia: Bulgarian National Committee for the International Biological Programme, 2020.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Não informado. Progress Report of the Bulgarian National Committee for the International Biological Programme. Bulgarian National Committee for the International Biological Programme, 2020.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.