Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hieu xanh » chieu xanh, hieu manh, hieu nganh
doc hieu » toc thieu, hoc thieu, hoc hien
trang va » hang va
tran van » luan van
dan than » dan chan, van than, dan toan
ban than » ban thanh, van thanh, ban hang

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 xanh - hanh ((trang va) or (tran van)) nhung cong ((dan than) OR (ban than)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu xanh - hanh ((trang va) OR (tran van)) nhung cong ((dan than) OR (ban than)) cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu xanh - hanh ((trang va) or (tran van)) nhung cong ((dan than) OR (ban than)) cau*".