Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu qua, diep quang
thong cong » trong cong, tong cong, thong thong
hieu quan » hieu qua, lieu quan, thien quan
tan khang » van khang, tao khang, tinh khang
tranh va » tranh van, trang va, trinh va
va thong » va thuong, va phuong, he thong
tan khan » tan nhan, toan khoan, tran khanh

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 quan)) - canh tranh va thong cong ((tan khan) OR (tan khang)) cap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thien ((hieu quang) OR (hieu quan)) - canh tranh va thong cong ((tan khan) OR (tan khang)) cap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thien ((hieu quang) or (hieu quan)) - canh tranh va thong cong ((tan khan) OR (tan khang)) cap".
• Adding a wildcard symbol may retrieve word variants: thien ((hieu quang) or (hieu quan)) - canh tranh va thong cong ((tan khan) OR (tan khang)) cap*.