Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu qua, diep quang
hieu quan » hieu qua, lieu quan, thien quan
hanh hang » thanh hang, hang hang, hanh han
cong manh » cong danh, duong manh, cong thanh
manh toan » thanh toan, anh tuan, tinh toan
ca nhung » cua nhung, cam nhung, ca nung
toan cau » toan cao, toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho ((hieu quang) OR (hieu quan)) - hanh hang ((ca nhung) or (va nhung)) cong manh toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho ((hieu quang) OR (hieu quan)) - hanh hang ((ca nhung) OR (va nhung)) cong manh toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((hieu quang) OR (hieu quan)) - hanh hang ((ca nhung) or (va nhung)) cong manh toan cau".
• Adding a wildcard symbol may retrieve word variants: ho ((hieu quang) OR (hieu quan)) - hanh hang ((ca nhung) or (va nhung)) cong manh toan cau*.