Perhaps you should try some spelling variations:
hanh dai » hanh tai, hanh dao, vanh dai
thuc van » thuc vat, thuc dan, thuc hanh
so sach » so sanh, bo sach, co sach
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va, hieu van
mang xa » lang xa, mang may, dang xay
sach va » sach xa, sach ha, sach dao
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach va ((mang xa) or (nang x)) hoi. hieu ve cam ((thuc van) OR (thuc va)) hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach va ((mang xa) OR (nang x)) hoi. hieu ve cam ((thuc van) OR (thuc va)) hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach va ((mang xa) or (nang x)) hoi. hieu ve cam ((thuc van) OR (thuc va)) hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach va ((mang xa) or (nang x)) hoi. hieu ve cam ((thuc van) OR (thuc va)) hanh dai cua tre*.