Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thuc dan » thuc hanh, hoc dan, thuc vat
hanh dai » hanh tai, hanh dao, vanh dai
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, mang xa, ang xa
thuc va » thuc vat, thuc day
su tien » su kien, su hien, tu tieng
dai su » dai sua, dai so, dan su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty xang xa hoi. ((hieu van) or (hieu qua)) cau ((thuc va) or (thuc dan)) hanh dai su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty xang xa hoi. ((hieu van) OR (hieu qua)) cau ((thuc va) OR (thuc dan)) hanh dai su tien.
• Adding a wildcard symbol may retrieve word variants: su sach ty xang xa hoi. ((hieu van) or (hieu qua)) cau ((thuc va) or (thuc dan)) hanh dai su tien*.