Perhaps you should try some spelling variations:
hieu manh » chieu xanh, hieu nganh, dieu hanh
canh tinh » hanh tinh, canh tranh, nhanh tinh
manh tinh » man tinh, manh binh, hanh tinh
hoc hieu » hoc thieu, hoc hien, doc hieu
cong dan » cong tan, huong dan, cong dong
cong san » cong tac
hang dau » hang va, hang tai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu manh - ((canh tinh) OR (manh tinh)) xay dung ((cong dan) or (cong san)) hang dau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu manh - ((canh tinh) OR (manh tinh)) xay dung ((cong dan) OR (cong san)) hang dau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu manh - ((canh tinh) OR (manh tinh)) xay dung ((cong dan) or (cong san)) hang dau".
• Adding a wildcard symbol may retrieve word variants: hoc hieu manh - ((canh tinh) OR (manh tinh)) xay dung ((cong dan) or (cong san)) hang dau*.