APA-referens (7:e uppl.)
Tough, A. M. (1979). The adult's learning projects: A fresh approach to theory and practice in adult learning (2nd ed.). Learning Concepts.
Chicago-referens (17:e uppl.)
Tough, Allen M. The Adult's Learning Projects: A Fresh Approach to Theory and Practice in Adult Learning. 2nd ed. Austin, Tex.: Learning Concepts, 1979.
MLA-referens (9:e uppl.)
Tough, Allen M. The Adult's Learning Projects: A Fresh Approach to Theory and Practice in Adult Learning. 2nd ed. Learning Concepts, 1979.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.