APA (7th ed.) Citation

PC Software Interest Group (Sunnyvale, Calif.). (1991). The PC-SIG encyclopedia of shareware: A comprehensive guide to low-cost software for IBM and compatibles (4th. ed.). PC-SIG.

Chicago Style (17th ed.) Citation

PC Software Interest Group (Sunnyvale, Calif.). The PC-SIG Encyclopedia of Shareware: A Comprehensive Guide to Low-cost Software for IBM and Compatibles. 4th. ed. Sunnyvale, Calif.: PC-SIG, 1991.

MLA (8th ed.) Citation

PC Software Interest Group (Sunnyvale, Calif.). The PC-SIG Encyclopedia of Shareware: A Comprehensive Guide to Low-cost Software for IBM and Compatibles. 4th. ed. PC-SIG, 1991.