Perhaps you should try some spelling variations:
bach khoan » bach khoa, cac khoan, bach hoa
khan thong » khap thong, khau thong, nhan thong
khoan phai » khong phai, khoa phau, khoan hoi
phai thong » phap thong, phai tuong, phan thong
thuc cach » thuoc sach, truoc cach, thuc hanh
sach tai » sach bai, sach tham, sach dao
tai thuc » thai thuc, tri thuc, dai thuc
cach kho » bach khoa, cach thoi, cach pha
kho khan » khoa kham, khoa than
sach dai » sach dao, sach bai, sach dat
dai truc » dai thuc, doan truc, dai trung
su sach » so sach, vu sach
tu sach » thu sach, te sach, tu cach

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 tai thuc cach kho khan thong ) or ( tu sach dai truc bach khoan phai thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach tai thuc cach kho khan thong ) OR ( tu sach dai truc bach khoan phai thong )).
• Adding a wildcard symbol may retrieve word variants: (( su sach tai thuc cach kho khan thong ) or ( tu sach dai truc bach khoan phai thong ))*.