Perhaps you should try some spelling variations:
ban hang » ngan hang
tu sach » thu sach, su sach, te sach
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang

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