?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.au=Nantha+Kumar+Subramaniam%2C+&rft.aulast=Nantha+Kumar+Subramaniam&rft.date=March+2009&rft.title=Learners'+Characteristics+and+Critical+Thinking+in+Online+Asynchronous+Collaborative+Learning+&rft.genre=proceeding