APA (7th ed.) Citation

Penna, C. V., Sewell, P. H., & Liebaers, H. (1970). The planning of library and documentation services (2d ed. rev. and enl.). Unesco.

Chicago Style (17th ed.) Citation

Penna, Carlos Víctor, Philip Hooper Sewell, and Herman Liebaers. The Planning of Library and Documentation Services. 2d ed. rev. and enl. Paris: Unesco, 1970.

MLA (8th ed.) Citation

Penna, Carlos Víctor, et al. The Planning of Library and Documentation Services. 2d ed. rev. and enl. Unesco, 1970.