Montira Khumdee และ Nattama Pongpairoj. (2013) VARIABLE PRODUCTION OF ENGLISH PAST TENSE MARKING BY L1 THAI LEARNERS: AN APPLICATION OF THE FAILED FUNCTIONAL FEATURES HYPOTHESIS. Chulalongkorn University:ม.ป.ท.Montira Khumdee และ Nattama Pongpairoj. 2013. VARIABLE PRODUCTION OF ENGLISH PAST TENSE MARKING BY L1 THAI LEARNERS: AN APPLICATION OF THE FAILED FUNCTIONAL FEATURES HYPOTHESIS. ม.ป.ท.:Chulalongkorn University;Montira Khumdee และ Nattama Pongpairoj. VARIABLE PRODUCTION OF ENGLISH PAST TENSE MARKING BY L1 THAI LEARNERS: AN APPLICATION OF THE FAILED FUNCTIONAL FEATURES HYPOTHESIS. ม.ป.ท.:Chulalongkorn University, 2013. Print.