Perhaps you should try some spelling variations:
thanh vi » hanh vi, thanh va, thanh ve
sach ty » sach tu, sach thu, xach tay
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 » so van, do van, ho 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 ty) or (sach y)) nang o hai. hieu va bac ((bo van) OR (vo van)) thanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ty) OR (sach y)) nang o hai. hieu va bac ((bo van) OR (vo van)) thanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) or (sach y)) nang o hai. hieu va bac ((bo van) OR (vo van)) thanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) or (sach y)) nang o hai. hieu va bac ((bo van) OR (vo van)) thanh vi cua tre*.