Perhaps you should try some spelling variations:
doi chieu » doc hieu, doi chi, mot chieu
hanh tran » hanh trang, thanh tran, hanh tram
ho chieu » theo chieu, hoc thieu, mot chieu
tran van » luan van
van bang » van ban, van nang, von bang
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: ((ho chieu) OR (doi chieu)) sach - hanh tran van bang ((huong dan) OR (cong san)) toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((ho chieu) OR (doi chieu)) sach - hanh tran van bang ((huong dan) or (cong san)) toan cau~".
• Adding a wildcard symbol may retrieve word variants: ((ho chieu) OR (doi chieu)) sach - hanh tran van bang ((huong dan) or (cong san)) toan cau*.