Perhaps you should try some spelling variations:
thieu quang » thien quan, trien quang, hieu quan
thanh trung » thanh tung
thuong cong » thong cong, thuong con, truong cong
thuong dong » phuong dong, tuong dong, chuong dong
hieu quang » hieu quan, hieu qua, diep quang
trung cua » truong cua, trung tuan, trung cap
san toan » van toan, dan toan, manh toan
toan ban » van ban

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 quang) OR (thieu quang)) - thanh trung cua ((thuong cong) or (thuong dong)) san toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu quang) OR (thieu quang)) - thanh trung cua ((thuong cong) OR (thuong dong)) san toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu quang) OR (thieu quang)) - thanh trung cua ((thuong cong) or (thuong dong)) san toan ban".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu quang) OR (thieu quang)) - thanh trung cua ((thuong cong) or (thuong dong)) san toan ban*.