5Dykes,J.Moore,K.And Wood,J.Virtual environments for student fieldwork using networked components[J].International Jounal of Geographical Information Sciene.1999.13 (4):397～416.
6University of Cambridge ＞ Department of Zoology ＞ Undergraduate taching ＞ Part Ⅱ Zoology Course.Information provided by webmaster@ zoo.cam.Ac.Uk.
7St.Petersburg State University ＞ Department of Invertebmte Zoology ＞ Courses List.Information provided by GitaPasker@yahoo.com.
