Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
van hanh » van thanh, ban hanh, van anh
huu phuc » huu thuc, huu phach, huu duc
sach ky » sac ky, sach y, sach ty
cau luc » cau truc, cau phuc
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va
nang o » nang co, nang ho, nang ro
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.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ky nang o hoi. ((hieu va) or (hieu qua)) ((cau luc) or (huu phuc)) van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky nang o hoi. ((hieu va) OR (hieu qua)) ((cau luc) OR (huu phuc)) van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: hoc sach ky nang o hoi. ((hieu va) or (hieu qua)) ((cau luc) or (huu phuc)) van hanh vi cua tre*.