Perhaps you should try some spelling variations:
hieu xanh » chieu xanh, hieu manh, hieu nganh
dung cong » dung trong
doc hieu » toc thieu, hoc thieu, hoc hien
tra tuan » tran tuan, tri tuan, ta tuan
tra quan » tri quan, tran quang, toan quan
cong tac » cong ty
toan cau » toan cao, toan tap, toan tai
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: doc hieu xanh - thanh ((tra tuan) OR (tra quan)) dung cong tac ((toan cau) OR (toan ban))~.
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - thanh ((tra tuan) or (tra quan)) dung cong tac ((toan cau) or (toan ban))*.