Perhaps you should try some spelling variations:
doi chieu » doi chi, ho chieu, mot chieu
dung cong » dung trong
manh toan » thanh toan, anh tuan, tinh toan
doc hieu » toc thieu, hoc thieu, hoc hien
tranh va » tranh van, trang va, trinh va
dan toan » van toan, dan than, xuan toan
va dung » van dung, va duong, vat dung

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doi chieu) OR (doc hieu)) sach - canh tranh va dung cong ((dan toan) or (manh toan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doi chieu) OR (doc hieu)) sach - canh tranh va dung cong ((dan toan) OR (manh toan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doi chieu) OR (doc hieu)) sach - canh tranh va dung cong ((dan toan) or (manh toan)) cau".
• Adding a wildcard symbol may retrieve word variants: ((doi chieu) OR (doc hieu)) sach - canh tranh va dung cong ((dan toan) or (manh toan)) cau*.