Não informado. (1957). Abstracts of Bulgarian Scientific Literature. Centre of Scientific Information and Documentation.
Chicago-referens (17:e uppl.)Não informado. Abstracts of Bulgarian Scientific Literature. Sofia: Centre of Scientific Information and Documentation, 1957.
MLA-referens (8:e uppl.)Não informado. Abstracts of Bulgarian Scientific Literature. Centre of Scientific Information and Documentation, 1957.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.