Cita APA (7a ed.)

Penna, C. V., Sewell, P. H., & Liebaers, H. (1972). The planning of library and documentation services (2nd ed. / rev. and enl. by P.H. Sewell and Herman Liebaers.). UNESCO.

Cita Chicago Style (17a ed.)

Penna, Carlos Víctor, Philip Hooper Sewell, y Herman Liebaers. The Planning of Library and Documentation Services. 2nd ed. / rev. and enl. by P.H. Sewell and Herman Liebaers. Paris: UNESCO, 1972.

Cita MLA (9a ed.)

Penna, Carlos Víctor, et al. The Planning of Library and Documentation Services. 2nd ed. / rev. and enl. by P.H. Sewell and Herman Liebaers. UNESCO, 1972.