APA-referens (7:e uppl.)
Willis, B. Distance education: Strategies and tools. Educational Technology Publications.
Chicago-referens (17:e uppl.)
Willis, Barry. Distance Education: Strategies and Tools. Englewood Cliffs, EUA: Educational Technology Publications.
MLA-referens (9:e uppl.)
Willis, Barry. Distance Education: Strategies and Tools. Educational Technology Publications.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.