Perhaps you should try some spelling variations:
trung tuan » trung thanh, trung tam, tran tuan
hieu lang » chieu sang, hieu quang, nhieu tang
trung cap » truong cao, trung tam
dang cong » dung cong
cong danh » cuong danh, cong dan, cong thanh
doi hieu » doi chieu, doc hieu, doi hien
toan ban » van ban

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 - hanh ((trung cap) OR (trung tuan)) dang cong danh ((toan tap) OR (toan ban))~.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - hanh ((trung cap) or (trung tuan)) dang cong danh ((toan tap) or (toan ban))*.