Perhaps you should try some spelling variations:
hieu manh » chieu xanh, hieu nganh, dieu hanh
cong thai » cong hai, hong thai, cong thanh
hoc hieu » hoc thieu, hoc hien, doc hieu
trang va » hang va
tran van » luan van
cong tai » cong tac, dong tai, cong tan
phan dau » phan tu, hang dau

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 ((trang va) or (tran van)) hang ((cong tai) or (cong thai)) phan dau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu manh - canh ((trang va) OR (tran van)) hang ((cong tai) OR (cong thai)) phan dau.
• Adding a wildcard symbol may retrieve word variants: hoc hieu manh - canh ((trang va) or (tran van)) hang ((cong tai) or (cong thai)) phan dau*.