Wittich, W. A., & Schuller, C. F. (1957). Audio-visual materials: Their nature and use (2a. ed.). Harper & Brothers.

Wittich, Walter Arno, and Charles Francis Schuller. Audio-visual Materials: Their Nature and Use. 2a. ed. Nueva York: Harper & Brothers, 1957.

Wittich, Walter Arno, and Charles Francis Schuller. Audio-visual Materials: Their Nature and Use. 2a. ed. Harper & Brothers, 1957.