Perhaps you should try some spelling variations:
ban thanh » ban hang
cach dua » cach cua, cach dung, cac du
ban hanh » ban hang
tu sach » thu sach, su sach, te sach
loi cua » loai cua, hoi cua, doi cua
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
hieu ve » hieu van
cua tre » cua te, cuu tre, cua triet
x hoi » xa hoi, o hoi, x ho

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 ky nang x hoi. ((hieu ve) OR (hieu va)) cach dua ((ban thanh) or (ban hanh)) loi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((hieu ve) OR (hieu va)) cach dua ((ban thanh) OR (ban hanh)) loi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. ((hieu ve) OR (hieu va)) cach dua ((ban thanh) or (ban hanh)) loi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu ve) OR (hieu va)) cach dua ((ban thanh) or (ban hanh)) loi cua tre*.