Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
trinh quan » tinh quang, trinh han
nhung cong » dung cong, thong cong, hang cong
cong toan » cong tan, cong hoan, cong tuan
phan cau » phan dau, phan tu, phan lap
phan cac » nhan cach, phan dau, phan lap
ho hieu » ho chieu, hoi hieu, nho hieu

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 - hanh ((trinh quan) or (trinh luat)) nhung cong toan ((phan cau) OR (phan cac))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu quang - hanh ((trinh quan) OR (trinh luat)) nhung cong toan ((phan cau) OR (phan cac)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu quang - hanh ((trinh quan) or (trinh luat)) nhung cong toan ((phan cau) OR (phan cac))".
• Adding a wildcard symbol may retrieve word variants: ho hieu quang - hanh ((trinh quan) or (trinh luat)) nhung cong toan ((phan cau) OR (phan cac))*.