Perhaps you should try some spelling variations:
nang noi » nang doc
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
sach ty » sach y, sach tu, sach thu
nang co » nang cao, nang doc, nang hoc
van hac » van hoc, van ha, van hai
cua tre » cua te, cuu tre, cua triet
hac so » hai so, ham so, hoc so
so van » su van, vo 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 ((nang co) or (nang noi)) hai. hieu van hac so van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((nang co) OR (nang noi)) hai. hieu van hac so van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach ty ((nang co) or (nang noi)) hai. hieu van hac so van hanh vi cua tre*.