Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
dinh vai » dinh van, dinh vi, dinh va
dang xay » dang van, van xay
vai cua » dai cua, hai cua, lai cua
va dinh » van dinh, va kinh, va tinh
dai lan » dai luan, dai han, dam lan
dai lao » dai thao, dai luan, chai lao
te sach » toc sach
sach ty » sach y, sach tu, sach thu
lang xa » lang ha, lang van
cua te » cua tu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty ((lang xa) OR (dang xay)) hoi. hieu vien ((dai lao) or (dai lan)) va dinh vai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((lang xa) OR (dang xay)) hoi. hieu vien ((dai lao) OR (dai lan)) va dinh vai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty ((lang xa) OR (dang xay)) hoi. hieu vien ((dai lao) or (dai lan)) va dinh vai cua te".
• Adding a wildcard symbol may retrieve word variants: te sach ty ((lang xa) OR (dang xay)) hoi. hieu vien ((dai lao) or (dai lan)) va dinh vai cua te*.