Perhaps you should try some spelling variations:
sach tranh » canh tranh
tranh thuc » trinh thuc, trang thuc, thanh thuy
cao khoan » cac khoan, tao khoang, lao khoa
ke thuong » te thuong, ky thuong, le thuong
hoach dan » hoach dat, hoach san, hoach toan
hoa thong » hoa trong, hoa khong, hoa thon
thuc cao » thuoc cao, thuc co, thuc can
khoan ke » khoan le, khoan va, toan ke
tu hoach » thu hoach, tu hach, quy hoach
dan thuc » dan toc, am thuc
cao khoa » lao khoa, bao khoa, cac khoa
khoa hoa » khoa khoa, khoa hoc, khoa hoi
tu sach » thu sach, su sach, te sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu sach tranh thuc cao khoan ke thuong ) or ( tu hoach dan thuc cao khoa hoa thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tranh thuc cao khoan ke thuong ) OR ( tu hoach dan thuc cao khoa hoa thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tranh thuc cao khoan ke thuong ) or ( tu hoach dan thuc cao khoa hoa thong ))*.