Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
luu van » cuu van, luan van, luu hanh
cam luu » tam luu
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
lang ha » long ha
nang ma » tang ma, sang ma, nang cao
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: su sach y ((nang ma) or (lang ha)) hoi. ((hieu ve) or (hieu van)) cam luu van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((nang ma) OR (lang ha)) hoi. ((hieu ve) OR (hieu van)) cam luu van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach y ((nang ma) or (lang ha)) hoi. ((hieu ve) or (hieu van)) cam luu van hanh vi cua tre*.