Não informado. (1978). Abstracts of bulgarian scientific literature. Central Institute for Scientific, Technical and Economic Information.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Abstracts of Bulgarian Scientific Literature. Sofia: Central Institute for Scientific, Technical and Economic Information, 1978.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Abstracts of Bulgarian Scientific Literature. Central Institute for Scientific, Technical and Economic Information, 1978.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.