Não informado. (1957). Abstracts of Bulgarian Scientific Literature. Centre of Scientific Information and Documentation.
Chicago-Zitierstil (17. Ausg.)Não informado. Abstracts of Bulgarian Scientific Literature. Sofia: Centre of Scientific Information and Documentation, 1957.
MLA-Zitierstil (8. Ausg.)Não informado. Abstracts of Bulgarian Scientific Literature. Centre of Scientific Information and Documentation, 1957.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.