Tough, A. M. (1979). The adult's learning projects: A fresh approach to theory and practice in adult learning (2d ed.). Learning Concepts.
Lua i Stíl Chicago (17ú heag.)Tough, Allen M. The Adult's Learning Projects: A Fresh Approach to Theory and Practice in Adult Learning. 2d ed. Austin, Tex.: Learning Concepts, 1979.
Lua MLA (8ú heag.)Tough, Allen M. The Adult's Learning Projects: A Fresh Approach to Theory and Practice in Adult Learning. 2d ed. Learning Concepts, 1979.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.