Hubbell. Sams Teach Yourself COBOL in 24 Hours (1.). Pearson India.
Čikaški stil citiranja (17. izdanje)Hubbell. Sams Teach Yourself COBOL in 24 Hours. 1. Pearson India.
MLA način citiranja (8. izdanje)Hubbell. Sams Teach Yourself COBOL in 24 Hours. 1. Pearson India.
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