Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, hieu ve
bo sach » co sach, hoc sach
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
cac tuc » cac toc, cac tu, cac tac
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa
vi cua » vai cua, di cua

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

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