APA (7th ed.) Citation

Verhelst, P. W., & Verster, N. F. (1981). PEP, an interactive programming system with an algol-like programming language (Preprint.).

Chicago Style (17th ed.) Citation

Verhelst, P. W., and N. F. Verster. PEP, an Interactive Programming System with an Algol-like Programming Language. Preprint. Amsterdam, 1981.

MLA (9th ed.) Citation

Verhelst, P. W., and N. F. Verster. PEP, an Interactive Programming System with an Algol-like Programming Language. Preprint. 1981.