Programmer's guide to GEM.

MLA

Balma, Phillip, and William Fitler. Programmer's Guide to Gem. Berkeley: Sybex, 1986.

APA

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

Chicago

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