Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien dai » hien dai
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
dai luc » dai luoc, dai luan, dai thuc
luc van » luoc van, luu van, duc van
tai duc » tai cuc, mai duc, tai du
duc tre » duoc tren, duc tien
co loi » co hoi

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: tu sach ky nang ((co loi) OR (co hoc)). hieu vien dai luc van hanh tai duc tre~.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((co loi) or (co hoc)). hieu vien dai luc van hanh tai duc tre*.