Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh vi » hanh vi, thanh va, thanh ve
sach tu » sach thu, cach tu, sach ty
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
va bac » van bac, va cac, va bai
bo van » vo van, so van, do van
vi cua » vai cua, di cua
o hai » co hai, so hai, o lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach tu) or (sach y)) nang o hai. hieu va bac bo van thanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach tu) OR (sach y)) nang o hai. hieu va bac bo van thanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: te ((sach tu) or (sach y)) nang o hai. hieu va bac bo van thanh vi cua tre*.