Perhaps you should try some spelling variations:
thuong cong » thong cong, thuong con, truong cong
thuong dong » phuong dong, tuong dong, chuong dong
nhanh mang » nhanh lang, nhanh quang, nhanh thang
hieu quan » hieu qua, lieu quan, thien quan
hanh mang » hanh trang, nhanh lang, thanh hang
doan van » doan va, hoang van, luan van
ho hieu » ho chieu, hoi hieu, nho hieu

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