Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cac thuc » cach thuc, cac thu, can thuc
dau tren » dat tren, dau tieng, dau trong
dau tien » van tien
te sach » toc sach
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, mang xa, ang xa
van cac » van hac, van cau, van bac
thuc va » thuc vat, thuc dan, thuc day
va luan » vay luan, van luan, va quan
luan ve » luat ve, luan va, quan ve

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