Perhaps you should try some spelling variations:
ban thanh » ban hang
thu sach » thuat sach, thuoc sach, thu hoach
cham cuc » cham cuu, pham cuc, pham chuc
ban hanh » ban hang
tu sach » su sach, te sach, tu cach
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 sach) 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 sach) OR (thu sach)) ky nang cao hoc. hieu vu cham cuc ((ban thanh) OR (ban hanh)) tai cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) 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 sach) or (thu sach)) ky nang cao hoc. hieu vu cham cuc ((ban thanh) OR (ban hanh)) tai cuc tre*.