Perhaps you should try some spelling variations:
nang doc » nang luc
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 noi, nang hoc
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
cac so » cac co, cac bo, cac ho
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 doc)) hai. hieu van cac so van hanh vi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty ((nang co) OR (nang doc)) hai. hieu van cac so van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ty ((nang co) OR (nang doc)) hai. hieu van cac so van hanh vi cua tre*.