Perhaps you should try some spelling variations:
hanh trang » thanh trung, canh tranh, hanh trinh
nhung cong » dung cong, thong cong, hang cong
hieu manh » chieu xanh, hieu nganh, dieu hanh
hanh tang » anh tang, hanh mang, hanh tung
dang cong » dung cong
hoc hieu » hoc thieu, hoc hien, doc hieu
san toan » van toan, dan toan, manh toan
toan cau » toan cao, toan ban, toan tap

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 tang) OR (hanh trang)) cua ((nhung cong) OR (dang cong)) san toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu manh - ((hanh tang) OR (hanh trang)) cua ((nhung cong) or (dang cong)) san toan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc hieu manh - ((hanh tang) OR (hanh trang)) cua ((nhung cong) or (dang cong)) san toan cau*.