APA (7th ed.) Citation

Perry Greg M. (1999). Sams teach yourself Visual Basic 6 in 21 days. SAMS.

Chicago Style (17th ed.) Citation

Perry Greg M. Sams Teach Yourself Visual Basic 6 in 21 Days. SAMS, 1999.

MLA (8th ed.) Citation

Perry Greg M. Sams Teach Yourself Visual Basic 6 in 21 Days. SAMS, 1999.

Warning: These citations may not always be 100% accurate.