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