Não informado. (1978). Abstracts of bulgarian scientific literature. Central Institute for Scientific, Technical and Economic Information.
Čikaški stil citiranja (17. izdanje)Não informado. Abstracts of Bulgarian Scientific Literature. Sofia: Central Institute for Scientific, Technical and Economic Information, 1978.
MLA način citiranja (8. izdanje)Não informado. Abstracts of Bulgarian Scientific Literature. Central Institute for Scientific, Technical and Economic Information, 1978.
Upozorenje: Ovi citati možda nisu uvijek 100% točni.