Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
tranh van » tran van, trinh van, thanh van
dang cong » dung cong
van dang » van dong, van dung, van nang
cong tac » cong ty
tac phan » tac pham, tai phan, tac phat
phan dau » phan tu, hang dau

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: toc ((hieu quan) OR (hieu qua)) - canh tranh van dang cong tac phan dau~.
• Adding a wildcard symbol may retrieve word variants: toc ((hieu quan) or (hieu qua)) - canh tranh van dang cong tac phan dau*.