Perhaps you should try some spelling variations:
thanh thong » thanh thuong, thanh hong, thanh thang
nhung cong » dung cong, thong cong, hang cong
hieu lang » chieu sang, hieu quang, nhieu tang
doc hieu » toc thieu, hoc thieu, hoc hien
thong tu » phong tuc, thong tin, thong ke
tan toan » tan tran, tap toan, van toan
toan cau » toan cao, toan ban, toan tap

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 - thanh thong tu ((nhung cong) or (dung trong)) tan toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu lang - thanh thong tu ((nhung cong) OR (dung trong)) tan toan cau.
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - thanh thong tu ((nhung cong) or (dung trong)) tan toan cau*.