Perhaps you should try some spelling variations:
hieu sach » chieu sach, hieu cach, dien sach
hanh tran » hanh trang, thanh tran, hanh tram
doc hieu » toc thieu, hoc thieu, hoc hien
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 tap, toan tai
toan ban » van ban

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