Perhaps you should try some spelling variations:
hanh tranh » canh tranh, hanh trinh, hanh trang
hieu manh » chieu xanh, hieu nganh, dieu hanh
tranh cua » doanh cua, manh cua
nhung don » nhung van, nhung bo
hang cong » dang cong, hang nong, bang cong
hoc hieu » hoc thieu, hoc hien, doc hieu
tap toan » tap doan, tap quan, bai toan

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: hoc hieu manh - hanh tranh cua ((nhung don) OR (hang cong)) ((tan tran) OR (tap toan)) cau~.
• Adding a wildcard symbol may retrieve word variants: hoc hieu manh - hanh tranh cua ((nhung don) or (hang cong)) ((tan tran) or (tap toan)) cau*.