Perhaps you should try some spelling variations:
thanh trung » thanh tung
hieu lang » chieu sang, hieu quang, nhieu tang
cua thong » cua thuong, cua tong, suat thong
cua khong » hua khong, cua phuong, cua thuong
doc hieu » toc thieu, hoc thieu, hoc hien
phan van » pham van, thanh van, luan van
ban dan » ban hang, ban hanh, ban quan

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 lang - thanh trung ((cua thong) or (cua khong)) phan van ban dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu lang - thanh trung ((cua thong) OR (cua khong)) phan van ban dan*.