Perhaps you should try some spelling variations:
chiet tach » chieu sach
trong tap » trong thap, tong tap, trong tan
cua dung » cua dong, qua dung, cua rung
cua dang » cua cong, cua ban
tap toan » tap doan, tap quan, bai toan
toan cau » toan cao, toan ban, toan tap
co sach » bo sach, cuon sach, hoc sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi ((co sach) or (chiet tach)) - canh tranh ((cua dung) or (cua dang)) trong tap toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((co sach) OR (chiet tach)) - canh tranh ((cua dung) OR (cua dang)) trong tap toan cau.
• Adding a wildcard symbol may retrieve word variants: doi ((co sach) or (chiet tach)) - canh tranh ((cua dung) or (cua dang)) trong tap toan cau*.