Perhaps you should try some spelling variations:
thanh tung » thanh cong
cua thuong » cua truong, cua phuong, ca thuong
hieu sang » chieu sang, hieu lang, hieu quang
cua khong » hua khong, cua phuong, cua cong
doc hieu » toc thieu, hoc thieu, hoc hien
cong tac » cong ty
tac phan » tac pham, tai phan, tac phat
phan cau » phan dau, phan cac, phan tu

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 - thanh tung ((cua khong) or (cua thuong)) cong tac phan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - thanh tung ((cua khong) OR (cua thuong)) cong tac phan cau.
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - thanh tung ((cua khong) or (cua thuong)) cong tac phan cau*.