Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
nhung cong » dung cong, thong cong, hang cong
trinh cua » tinh cua, trinh quan, trinh luan
toan phan » thanh phan, toan ban, hoa phan
tan phan » than phan, van phan, tai phan
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 cua) or (trinh luat)) nhung cong ((tan phan) OR (toan phan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu quang - hanh ((trinh cua) OR (trinh luat)) nhung cong ((tan phan) OR (toan phan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu quang - hanh ((trinh cua) or (trinh luat)) nhung cong ((tan phan) OR (toan phan)) cau".
• Adding a wildcard symbol may retrieve word variants: ho hieu quang - hanh ((trinh cua) or (trinh luat)) nhung cong ((tan phan) OR (toan phan)) cau*.