Perhaps you should try some spelling variations:
thieu nien » thien nhien
hieu hien » bieu hien, dieu hien, chieu chien
hanh vai » hanh vi, hanh va, hanh tai
cach tu » cach thuc
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
cac tu » cac thu, cac du, tac tu
x hoi » xa hoi, o hoi, x ho

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang x hoi. ((thieu nien) or (hieu hien)) ((cac tu) OR (cach tu)) va hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((thieu nien) OR (hieu hien)) ((cac tu) OR (cach tu)) va hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. ((thieu nien) or (hieu hien)) ((cac tu) OR (cach tu)) va hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((thieu nien) or (hieu hien)) ((cac tu) OR (cach tu)) va hanh vai cua tre*.