Cognitive, social and teaching presence in a virtual world and a text chat. - Tomoko Watanabe Traphagan; Yueh-hui Vanessa Chiang; Hyeseung Maria Chang; Benjaporn Wattanawaha; Haekyung Lee; Michael Charles Mayrath; Jeongwon Woo; Hyo-Jin Yoon; Min Jung Jee; Paul E. Resta (Comput. Educ., 2010)