Perhaps you should try some spelling variations:
chieu xanh » chieu sach, chieu sang, chieu tinh
hanh trang » thanh trung, canh tranh, hanh trinh
nhung cong » dung cong, thong cong, nhung don
doi chieu » doc hieu, doi chi, ho chieu
hang cong » dang cong, hang nong, bang cong
trang va » tran van, hang va

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: doi chieu xanh - hanh trang va ((nhung cong) OR (hang cong)) ((bai toan) OR (bai tap)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi chieu xanh - hanh trang va ((nhung cong) or (hang cong)) ((bai toan) OR (bai tap)) cau~".
• Adding a wildcard symbol may retrieve word variants: doi chieu xanh - hanh trang va ((nhung cong) or (hang cong)) ((bai toan) OR (bai tap)) cau*.