Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu qua, diep quang
nhanh mang » hanh mang, nhanh quang, nhanh thang
nhanh lang » nhanh quang, nhanh thang, nhan dang
hieu quan » hieu qua, lieu quan, thien quan
dung cong » dung trong
cong van » cong vang, cong san, song van
van toan » van tuan, van tan, van thanh
toan ban » van ban
va dung » van dung, va duong, vat dung

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: hoi ((hieu quang) OR (hieu quan)) - ((nhanh mang) OR (nhanh lang)) va dung cong van toan ban~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoi ((hieu quang) OR (hieu quan)) - ((nhanh mang) or (nhanh lang)) va dung cong van toan ban~".
• Adding a wildcard symbol may retrieve word variants: hoi ((hieu quang) OR (hieu quan)) - ((nhanh mang) or (nhanh lang)) va dung cong van toan ban*.