Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
doi chieu » doc hieu, doi chi, ho chieu
hanh tran » hanh trang, thanh tran, hanh tram
song xanh » song hanh, hoang xanh, duong xanh
xanh than » danh thanh, danh thang, manh thang
ban song » bang song, bean song, ban cong
than tap » toan tap, han tap, phan tap

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doi chieu sach - ((hanh tran) or (canh tranh)) van ban song xanh than tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi chieu sach - ((hanh tran) OR (canh tranh)) van ban song xanh than tap.
• Adding a wildcard symbol may retrieve word variants: doi chieu sach - ((hanh tran) or (canh tranh)) van ban song xanh than tap*.