Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, diep quang
khong cong » thong cong, khong cang, chong cong
doanh hua » doanh ha, doanh khoa, doanh luan
doanh cua » doanh luan
cong san » cong tac
san van » tan van, luan van, tran van
van tap » van tai, van tan, han tap

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thien ((hieu quang) OR (hieu qua)) - hanh ((doanh hua) or (doanh cua)) khong cong san van tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thien ((hieu quang) OR (hieu qua)) - hanh ((doanh hua) OR (doanh cua)) khong cong san van tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thien ((hieu quang) OR (hieu qua)) - hanh ((doanh hua) or (doanh cua)) khong cong san van tap".
• Adding a wildcard symbol may retrieve word variants: thien ((hieu quang) OR (hieu qua)) - hanh ((doanh hua) or (doanh cua)) khong cong san van tap*.