Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hanh vai » hanh vi, hanh va, hanh tai
vai cua » dai cua, hai cua, lai cua
van lam » van nam
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
xac va » tac va, ac va, bac va
luc va » duc va, tuc va, loc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach y ((nang x) or (nang ma)) hoi. hieu van lam ((xac va) or (luc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y ((nang x) OR (nang ma)) hoi. hieu van lam ((xac va) OR (luc va)) hanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach y ((nang x) or (nang ma)) hoi. hieu van lam ((xac va) or (luc va)) hanh vai cua tre*.