Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
trinh quan » tinh quang, trinh luat, trinh han
hieu sang » chieu sang, hieu lang, nhieu tang
hang cong » dang cong, hang nong, bang cong
cong manh » cong danh, duong manh, cong thanh
manh toan » thanh toan, anh tuan, tinh 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 sang) OR (hieu quang)) - hanh ((trinh quan) or (tinh chat)) hang cong manh toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu quang)) - hanh ((trinh quan) OR (tinh chat)) hang cong manh toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) OR (hieu quang)) - hanh ((trinh quan) or (tinh chat)) hang cong manh toan ban".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) OR (hieu quang)) - hanh ((trinh quan) or (tinh chat)) hang cong manh toan ban*.