Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
hieu sach » hieu cach, dien sach, hieu cac
hanh tran » hanh trang, thanh tran, hanh tram
tran van » luan van
van nang » van quang, van ban, van dong
cong dan » cong tan, huong dan, cong dong
cong san » cong tac
toan cau » toan cao, toan ban, toan tap

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 sach) OR (chieu sach)) - hanh tran van nang ((cong dan) OR (cong san)) toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sach) OR (chieu sach)) - hanh tran van nang ((cong dan) or (cong san)) toan cau~".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sach) OR (chieu sach)) - hanh tran van nang ((cong dan) or (cong san)) toan cau*.