Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
van hoi » van hoc, van hoe, van loi
hieu va » lieu va, hieu qua
cac luc » cau luc, cac nuoc, cac cuoc
kem cua » em cua, keo cua, diem cua
cua tre » cua te, cuu tre, cua triet

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