Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
va hanh » van hanh, va thanh, va danh
cac tuc » cac toc, cac tac, cac nuoc
sach ky » sac ky, sach y, sach ty
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet
cac tu » cac thu, cach tu, cac du
vi cua » vai cua, di cua
o hoi » co hoi, o hoc, o hai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang ((5 hoi) OR (o hoi)). hieu van ((cac tuc) OR (cac tu)) va hanh vi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang ((5 hoi) or (o hoi)). hieu van ((cac tuc) OR (cac tu)) va hanh vi cua tre~".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang ((5 hoi) or (o hoi)). hieu van ((cac tuc) OR (cac tu)) va hanh vi cua tre*.