APA (7th ed.) Citation

(1987). X/OPEN portability guide. Vol. 3. System V specification. Supplementary definitions. Elsevier Science Publishers.

Chicago Style (17th ed.) Citation

X/OPEN Portability Guide. Vol. 3. System V Specification. Supplementary Definitions. Amsterdam: Elsevier Science Publishers, 1987.

MLA (9th ed.) Citation

X/OPEN Portability Guide. Vol. 3. System V Specification. Supplementary Definitions. Elsevier Science Publishers, 1987.

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