?url_ver=Z39.88-2004&rft_id=10.1109%2FICCISci.2012.6297299&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aufirst=N.V.&rft.aulast=Dung&rft.au=Dung%2C+N.V.&rft.isbn=9781467319386&rft.title=Towards+the+development+of+an+online+adaptive+system+framework+for+English+learning+using+perturbation+learner+model&rft.date=2012&rft.genre=proceeding