Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh vai » hanh vi, hanh va, hanh tai
vai cua » dai cua, hai cua, lai cua
truc va » thuc va, thuc vat, trung va
van cam » van nam, van lam, van cau
sach ty » sach tu, sach thu, xach tay
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, tuc xa, duc va
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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) or (sach y)) nang o hoi. hieu van cam ((tuc va) or (truc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach y)) nang o hoi. hieu van cam ((tuc va) OR (truc va)) hanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach y)) nang o hoi. hieu van cam ((tuc va) or (truc va)) hanh vai cua tre*.