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
su sach » vu sach
so sach » so sanh, bo sach, co sach
nang xa » nang x, lang xa, nang ma
cac tac » cac toc, cac bac, cac dac
tac van » tac vang, cac van, tac va
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
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) or (so sach)) y nang xa hoi. ((hieu van) or (thien van)) cac tac van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) y nang xa hoi. ((hieu van) OR (thien van)) cac tac van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) y nang xa hoi. ((hieu van) or (thien van)) cac tac van hanh vi cua tre*.