Perhaps you should try some spelling variations:
hanh tranh » canh tranh, hanh trinh, hanh trang
luan hang » luan nang, luan hung, luan tang
theo chu » theo chieu, cho chu, chao chu
chu sach » cau sach, thu sach, chieu sach
luan han » luan hoan, luan phan, luan van
tap toan » tap doan, tap quan, bai toan
van tuan » van quan, van ban, anh tuan

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: theo chu sach - hanh tranh ((luan hang) OR (luan han)) cong ((tap toan) OR (van tuan)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo chu sach - hanh tranh ((luan hang) OR (luan han)) cong ((tap toan) or (van tuan)) cau~".
• Adding a wildcard symbol may retrieve word variants: theo chu sach - hanh tranh ((luan hang) OR (luan han)) cong ((tap toan) or (van tuan)) cau*.