Heidt, E. U. (1978). Instructional media and the individual learner: A classification and systems appraisal (Rev. and enl. English ed.). Kagan Page.

Heidt, Erhard U. Instructional Media and the Individual Learner: A Classification and Systems Appraisal. Rev. and enl. English ed. London: Kagan Page, 1978.

Heidt, Erhard U. Instructional Media and the Individual Learner: A Classification and Systems Appraisal. Rev. and enl. English ed. Kagan Page, 1978.