Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
te sach » toc sach
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, ang xa, dang xay
mang xa » lang xa, mang may, dang xay
hieu ve » hieu va, hieu van
cac thu » cach thuc, cac thoi
va luan » vay luan, van luan, va quan
luan vi » quan vi, luan va, luan ve
ve cac » va cac, vien cac
thu va » thuc va, thue va, tu va
vi dau » vi dai, va dau, bi dau

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 ((xang xa) or (mang xa)) hoi. hieu ve cac thu va luan vi dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((xang xa) OR (mang xa)) hoi. hieu ve cac thu va luan vi dau tren.
• Adding a wildcard symbol may retrieve word variants: te sach ty ((xang xa) or (mang xa)) hoi. hieu ve cac thu va luan vi dau tren*.