Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
doc hieu » toc thieu, hoc thieu, hoc hien
trang va » hang va
tran van » luan van
cong tac » cong ty
tac than » tac thanh, tam than, tac nhan
than cao » toan cao, thai cao, than cap
doi chi » doi khi

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