Perhaps you should try some spelling variations:
chat xuc » chat huu, cam xuc, chao xu
ban hang » ngan hang
tu sach » thu sach, su sach, te sach
hai cua » thai cua, dai cua, hoi cua
va hanh » van hanh, va thanh, va danh
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
hieu ve » hieu van
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet

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