Wittich, W. A., & Schuller, C. F. (1973). Instructional technology: Its nature and use (5th ed.). Harper & Row.
Lua i Stíl Chicago (17ú heag.)Wittich, Walter Arno, agus Charles Francis Schuller. Instructional Technology: Its Nature and Use. 5th ed. New York: Harper & Row, 1973.
Lua MLA (8ú heag.)Wittich, Walter Arno, agus Charles Francis Schuller. Instructional Technology: Its Nature and Use. 5th ed. Harper & Row, 1973.
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