Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
cua tong » cua cong, cua dong, cua song
cua nong » cua cong, cuu nong, cua dong
cong van » cong vang, cong san, song van
van toan » van tuan, van tan, van thanh
toan ban » van ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo ((toc sach) or (thuoc sach)) - canh tranh ((cua tong) OR (cua nong)) cong van toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((toc sach) OR (thuoc sach)) - canh tranh ((cua tong) OR (cua nong)) cong van toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo ((toc sach) or (thuoc sach)) - canh tranh ((cua tong) OR (cua nong)) cong van toan ban".
• Adding a wildcard symbol may retrieve word variants: theo ((toc sach) or (thuoc sach)) - canh tranh ((cua tong) OR (cua nong)) cong van toan ban*.