Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, nhung don
thanh tung » thanh cong
hang cong » dang cong, hang nong, bang cong
hoc hieu » hoc thieu, hoc hien, doc hieu
hieu luc » hieu luat, hieu qua
tung cua » trung cua, tuong cua, dung cua
dan chan » dan gian, dan ca, van chat
chan cau » phan cau, can cau, chinh cau

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu luc - thanh tung cua ((nhung cong) or (hang cong)) dan chan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu luc - thanh tung cua ((nhung cong) OR (hang cong)) dan chan cau.
• Adding a wildcard symbol may retrieve word variants: hoc hieu luc - thanh tung cua ((nhung cong) or (hang cong)) dan chan cau*.