Heidt, E. U. (1978). Instructional media and the individual learner: A classification and systems appraisal (Rev. and enl. English ed.). Kagan Page.
Lua i Stíl Chicago (17ú heag.)Heidt, Erhard U. Instructional Media and the Individual Learner: A Classification and Systems Appraisal. Rev. and enl. English ed. London: Kagan Page, 1978.
Lua MLA (8ú heag.)Heidt, Erhard U. Instructional Media and the Individual Learner: A Classification and Systems Appraisal. Rev. and enl. English ed. Kagan Page, 1978.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.