Perhaps you should try some spelling variations:
ban doanh » van doanh, san doanh, ban danh
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
nam dua » nam da, nam mua, nam qua
tai cuu » tai cuc, tai buu, tai cua
cuu tre » cua tre, cau tren, cau treo

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 nang ((mai hoi) or (ma hoa)). hieu van ((nam dua) or (nam cua)) ban doanh tai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((mai hoi) OR (ma hoa)). hieu van ((nam dua) OR (nam cua)) ban doanh tai cuu tre.
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((mai hoi) or (ma hoa)). hieu van ((nam dua) or (nam cua)) ban doanh tai cuu tre*.