Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu vien » hieu viec, thieu nien, hieu tieng
hieu hien » bieu hien, dieu hien, chieu chien
va thanh » gia thanh, va tinh, le thanh
cac dai » cac dan, cac bai, can dai
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
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: su sach ky nang o hoi. ((hieu vien) or (hieu hien)) cac dai ((va thanh) OR (ban thanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang o hoi. ((hieu vien) OR (hieu hien)) cac dai ((va thanh) OR (ban thanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang o hoi. ((hieu vien) or (hieu hien)) cac dai ((va thanh) OR (ban thanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang o hoi. ((hieu vien) or (hieu hien)) cac dai ((va thanh) OR (ban thanh)) vi cua tre*.