Perhaps you should try some spelling variations:
hieu xanh » chieu xanh, hieu manh, hieu nganh
dang cong » dung cong
van thanh » ban thanh, van tuan
doc hieu » toc thieu, hoc thieu, hoc hien
canh ban » can ban, canh dan, doanh ban
canh van » anh van, can van, cach van
cua dang » cua cong, cua ban
van than » van thang, van tuan, van phan

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 - ((canh ban) OR (canh van)) cua dang cong ((van than) OR (van thanh)) cap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu xanh - ((canh ban) OR (canh van)) cua dang cong ((van than) or (van thanh)) cap~".
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - ((canh ban) OR (canh van)) cua dang cong ((van than) or (van thanh)) cap*.