Perhaps you should try some spelling variations:
van hang » van khang, van hoang, van thang
luc van » luoc van, luu van, duc van
nam luc » nang luc, nhan luc, nam thuc
hieu va » hieu qua
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
xac ky » cac ky, sac ky, bac ky
di cau » da cau, diem cau
su xac » pu xac, su cac
di du » li du

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: su xac ky tang xa hoi. ((hieu va) OR (lieu va)) nam luc van hang ((di cau) OR (di du)) tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su xac ky tang xa hoi. ((hieu va) OR (lieu va)) nam luc van hang ((di cau) or (di du)) tren~".
• Adding a wildcard symbol may retrieve word variants: su xac ky tang xa hoi. ((hieu va) OR (lieu va)) nam luc van hang ((di cau) or (di du)) tren*.