Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, nhung don
hiem ngan » kim ngan, viem gan
hanh sinh » hanh tinh, hanh dinh, hinh sinh
hang cong » dang cong, hang nong, bang cong
van thanh » ban thanh, van tuan
doc hiem » doc hieu, hoc hien, doc viet
sinh cua » manh cua, dinh cuu, sinh va
van toan » van tuan, van tan, manh toan

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc hiem ngan - hanh sinh cua ((nhung cong) or (hang cong)) ((van toan) OR (van thanh)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hiem ngan - hanh sinh cua ((nhung cong) OR (hang cong)) ((van toan) OR (van thanh)) cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hiem ngan - hanh sinh cua ((nhung cong) or (hang cong)) ((van toan) OR (van thanh)) cao".
• Adding a wildcard symbol may retrieve word variants: doc hiem ngan - hanh sinh cua ((nhung cong) or (hang cong)) ((van toan) OR (van thanh)) cao*.