Penna, C. V., Sewell, P. H., & Liebaers, H. (1972). The planning of library and documentation services (2nd. ed. rev. and enlarged.). [Paris]: Unesco.
Παραπομπή Chicago StylePenna, C. V., P. H. Sewell, and Herman Liebaers. The Planning of Library and Documentation Services. 2nd. ed. rev. and enlarged. [Paris]: Unesco, 1972.
Παραπομπή MLAPenna, C. V., P. H. Sewell, and Herman Liebaers. The Planning of Library and Documentation Services. 2nd. ed. rev. and enlarged. [Paris]: Unesco, 1972.
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