Engelmann, H. O. (1966). Essays in social theory and social organization. W. C. Brown Book Co..
Lua i Stíl Chicago (17ú heag.)Engelmann, Hugo O. Essays in Social Theory and Social Organization. Dubuque, Iowa: W. C. Brown Book Co., 1966.
Lua MLA (8ú heag.)Engelmann, Hugo O. Essays in Social Theory and Social Organization. W. C. Brown Book Co., 1966.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.