Perhaps you should try some spelling variations:
ban thanh » ban hang
thu sach » tu sach, thuat sach, thuoc sach
cham cuc » cham cuu, pham cuc, pham chuc
ban hanh » ban hang
tu cach » tu cac
cao hoc » co hoc, cho hoc, chat hoc
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
cuc tre » duc tre, cua tre, cuu tre

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (thu sach)) ky nang cao hoc. hieu vu cham cuc ((ban thanh) or (ban hanh)) tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (thu sach)) ky nang cao hoc. hieu vu cham cuc ((ban thanh) OR (ban hanh)) tai cuc tre.
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (thu sach)) ky nang cao hoc. hieu vu cham cuc ((ban thanh) or (ban hanh)) tai cuc tre*.