Perhaps you should try some spelling variations:
hieu sach » chieu sach, hieu cach, hieu cac
dien sach » dien anh
tranh cua » doanh cua, manh cua
cua chung » cua nhung, luan chung, luat chung
chinh cau » chinh chau, chinh ca, chinh can
cong dan » cong san, huong dan, cong dong
cong tan » cong tac, cong san, cong thanh

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sach) or (dien sach)) - canh tranh cua chung ((cong dan) or (cong tan)) chinh cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sach) OR (dien sach)) - canh tranh cua chung ((cong dan) OR (cong tan)) chinh cau.
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sach) or (dien sach)) - canh tranh cua chung ((cong dan) or (cong tan)) chinh cau*.