Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thu sach » tu sach, thuat sach, thuoc sach
cua dua » cua duc, ca dua, cua dia
hai cua » thai cua, dai cua, hoi cua
vai cua » dai cua, lai cua, bai cua
dua ban » dia ban, cua ban, qua ban
hieu va » lieu va, hieu qua
ky tang » ky nang, ky dang, kho tang
ky sang » ky nang, ky dang, duy sang
va cua » va chua, via cua, ca cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ((ky sang) OR (ky tang)) ma hoa. hieu va cua dua ban thanh ((vai cua) or (hai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ky sang) OR (ky tang)) ma hoa. hieu va cua dua ban thanh ((vai cua) OR (hai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((ky sang) OR (ky tang)) ma hoa. hieu va cua dua ban thanh ((vai cua) or (hai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ((ky sang) OR (ky tang)) ma hoa. hieu va cua dua ban thanh ((vai cua) or (hai cua)) tre*.