Holmberg, B. (2003). Distance education in essence - An overview of theory and practice in the early twenty-first century (2nd ed.). Oldenburg:Bibliotheks- und Informationssystem der Universität Oldenburg. pp. 107-113 107
Holmberg, B. (2003). Distance education in essence - An overview of theory and practice in the
early twenty-first century (2nd ed.). Oldenburg:Bibliotheks- und Informationssystem der Universität
Oldenburg. pp. 107-113
107