JOURNAL OF SCIIoNCI''''; Ol'''''''' HNUH iMlucational Sci, 2011, \o l 5(i, Xo I, i)p 24 28 sO DUNG HE THLfC L U O N G TRONG TAM GIAC VUONG VAO DAY HOC GIAI BAI TOAN CAU PHUONG CAC HINH P H A N G V A D U N G DO[.]
.JOURNAL OF SCIIoNCI'; Ol'' HNUH iMlucational Sci, 2011, \ o l 5(i, Xo I, i)p 24-28 s O DUNG HE THLfC L U O N G TRONG TAM GIAC VUONG VAO DAY HOC GIAI BAI TOAN CAU PHUONG CAC HINH P H A N G V A D U N G DO THI H A M SO Cliti Tronp, T h a n h Tritang Dai li.oc Vinh Iv-mail: thanhchul951