Perhaps you should try some spelling variations:
khau thong » khau thuong, khap thong, khau tong
sach tren » sach tien, sach tranh
tren thuc » trien thuc, tron thuc, trinh thuc
thuc cach » thuoc sach, truoc cach, thuc hanh
cach khoa » bach khoa, cac khoa, cac khoan
khoa khau » khoa kham, khoa phau, khoa chau
cach hoan » cac khoan, hach toan, sach han
su sach » vu sach
so sach » so sanh, bo sach, co sach
hoan he » hoa he, toan he, hoan thue

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su sach tren thuc cach khoa khau thong ) or ( so sach tren thuc cach hoan he thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach tren thuc cach khoa khau thong ) OR ( so sach tren thuc cach hoan he thong ))*.