APA (7th ed.) Citation

Balma, P., & Fitler, W. (1986). Programmer's guide to GEM. Sybex.

Chicago Style (17th ed.) Citation

Balma, Phil, and William Fitler. Programmer's Guide to GEM. Berkeley u.a: Sybex, 1986.

MLA (9th ed.) Citation

Balma, Phil, and William Fitler. Programmer's Guide to GEM. Sybex, 1986.