Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cap » vien cac, vien cao, vien can
cap nuoc » dat nuoc
van hanh » van thanh, van anh, van ban
ban hanh » ban hang
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
co hoi » co loi

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 ((co hoi) or (co hoc)). hieu vien cap nuoc ((van hanh) OR (ban hanh)) tri cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((co hoi) OR (co hoc)). hieu vien cap nuoc ((van hanh) OR (ban hanh)) tri cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((co hoi) or (co hoc)). hieu vien cap nuoc ((van hanh) OR (ban hanh)) tri cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((co hoi) or (co hoc)). hieu vien cap nuoc ((van hanh) OR (ban hanh)) tri cua tre*.