Perhaps you should try some spelling variations:
quan trong » gian trong
hieu xanh » chieu xanh, hieu manh, hieu nganh
canh manh » lanh manh, canh tranh, cach mang
qua trong » qua trinh, qua song, qua cong
doc hieu » toc thieu, hoc thieu, hoc hien
cong tan » cong tac, cong thanh, cong ty
cong san » cong tac

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 - canh manh ((qua trong) OR (quan trong)) ((cong tan) OR (cong san)) van ban~.
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - canh manh ((qua trong) or (quan trong)) ((cong tan) or (cong san)) van ban*.