Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
duong cong » dung cong, luong cong, duong trong
cua duong » cua dong, cua huong, qua duong
hoc hieu » hoc thieu, hoc hien, doc hieu
hanh han » hanh nhan, hanh phan, hanh san
cong tan » cong tac, cong san, cong thanh
toan ban » van ban
han cua » hang cua, nhan cua, than cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu quang - hanh han cua duong cong tan ((toan tap) or (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu quang - hanh han cua duong cong tan ((toan tap) OR (toan ban)).
• Adding a wildcard symbol may retrieve word variants: hoc hieu quang - hanh han cua duong cong tan ((toan tap) or (toan ban))*.