Perhaps you should try some spelling variations:
hanh trang » thanh trung, canh tranh, hanh trinh
hieu xanh » chieu xanh, hieu manh, hieu nganh
trang xay » trong xay, trang xa, trang va
doc hieu » toc thieu, hoc thieu, hoc hien
cong ban » cong bang, cong tan, cong dan
cong san » cong tac
toan cau » toan cao, toan ban, toan tap
phan dau » phan tu, hang dau

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 - hanh trang xay dung ((cong ban) OR (cong san)) ((toan cau) OR (phan dau))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu xanh - hanh trang xay dung ((cong ban) OR (cong san)) ((toan cau) or (phan dau))~".
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - hanh trang xay dung ((cong ban) OR (cong san)) ((toan cau) or (phan dau))*.