Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
cua thong » cua thuong, cua khong, cua tong
doc hieu » toc thieu, hoc thieu, hoc hien
canh van » anh van, can van, cach van
cong tan » cong tac, cong san, cong thanh
toan tap » toan ban
toan cao » toan ban
van cua » vang cua, ban cua, dan cua

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 lang - canh van cua thong cong tan ((toan tap) or (toan cao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu lang - canh van cua thong cong tan ((toan tap) OR (toan cao)).
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - canh van cua thong cong tan ((toan tap) or (toan cao))*.