Perhaps you should try some spelling variations:
trung thanh » truong thanh
nhung cong » dung cong, thong cong, hang cong
hieu lang » chieu sang, hieu quang, nhieu tang
doi hieu » doi chieu, doc hieu, doi hien
cong dan » cong san, cong tan, huong dan
dan khan » dan khanh, dan chan, dan than
khan ap » khan cap, han ap, khan dam

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doi hieu lang - thanh ((trung tam) OR (trung thanh)) nhung cong dan khan ap~.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - thanh ((trung tam) or (trung thanh)) nhung cong dan khan ap*.