Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hieu sang » chieu sang, hieu lang, hieu quang
doc hieu » toc thieu, hoc thieu, hoc hien
cong san » cong tac
toan cau » toan cao, toan ban, toan tai
toan tap » toan ban
cong va » dong va, cong ha, cong tac

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 sang - thanh cong va nhung cong san ((toan cau) or (toan tap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - thanh cong va nhung cong san ((toan cau) OR (toan tap)).
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - thanh cong va nhung cong san ((toan cau) or (toan tap))*.