Perhaps you should try some spelling variations:
ban thanh » ban hanh
ban hang » ngan hang
tu sach » thu sach, su sach, te sach
hai cua » thai cua, dai cua, hoi cua
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
tang ma » tang van
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam

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 ((tang ma) or (mang may)) hoi. hieu ve cam xuc ((ban thanh) or (ban hang)) hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((tang ma) OR (mang may)) hoi. hieu ve cam xuc ((ban thanh) OR (ban hang)) hai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((tang ma) or (mang may)) hoi. hieu ve cam xuc ((ban thanh) or (ban hang)) hai cua tre*.