Perhaps you should try some spelling variations:
thanh tuong » thanh thuong, thanh tung, thanh huong
cong thang » cong thanh, cang thang, cong thong
hieu sang » chieu sang, hieu lang, hieu quang
tuong cua » truong cua, huong cua, thong cua
cong tang » cong tan, cong lang, cong vang
doc hieu » toc thieu, hoc thieu, hoc hien
cua bang » chua bang, cua ban, cua dang

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 tuong cua bang ((cong tang) or (cong thang)) van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - thanh tuong cua bang ((cong tang) OR (cong thang)) van ban*.