APA (7th ed.) Citation

(1990). Unix system v release 4, user's guide. Unix System Laboratories, Inc.

Chicago Style (17th ed.) Citation

Unix System V Release 4, User's Guide. USA: Unix System Laboratories, Inc, 1990.

MLA (9th ed.) Citation

Unix System V Release 4, User's Guide. Unix System Laboratories, Inc, 1990.

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