Cita APA (7th ed.)

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

Cita Chicago (17th ed.)

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

Cita MLA (8th ed.)

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