Perhaps you should try some spelling variations:
hieu xanh » chieu xanh, hieu manh, hieu nganh
mong luan » tong luan, cong luan, dong luan
hang luan » tang luan, dung luan
dong cong » duong cong, dung cong, dang cong
doc hieu » toc thieu, hoc thieu, hoc hien
dan toan » van toan, manh toan, xuan toan
dan than » dan chan, ban than, van than

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 ((mong luan) OR (hang luan)) dong cong ((dan toan) OR (dan than)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu xanh - hanh ((mong luan) or (hang luan)) dong cong ((dan toan) OR (dan than)) cau~".
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - hanh ((mong luan) or (hang luan)) dong cong ((dan toan) OR (dan than)) cau*.