Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
hieu sang » chieu sang, hieu lang, nhieu tang
hanh tang » hanh trang, anh tang, hanh mang
tang luan » dung luan
luan cong » luat cong, luong cong, luan chung
cong cong » cong dong, trong cong, dung cong
van chat » cao chat

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sang) OR (hieu quang)) - hanh tang luan cong cong ((dan gian) or (van chat)) ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu quang)) - hanh tang luan cong cong ((dan gian) OR (van chat)) ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) OR (hieu quang)) - hanh tang luan cong cong ((dan gian) or (van chat)) ban".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) OR (hieu quang)) - hanh tang luan cong cong ((dan gian) or (van chat)) ban*.