Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh ca » thanh cha, thanh cac, thanh ha
duoc ban » duc ban, quoc ban, buoc ban
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
va nay » va ngay, va cay
ma hoi » xa hoi, ma hoa, me hoi
ca cua » co cua
va nam » van nam, ha nam

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky sang ((ma hoi) OR (mai hoi)). lieu ((va nam) or (va nay)) duoc ban thanh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky sang ((ma hoi) OR (mai hoi)). lieu ((va nam) OR (va nay)) duoc ban thanh ca cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky sang ((ma hoi) OR (mai hoi)). lieu ((va nam) or (va nay)) duoc ban thanh ca cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ky sang ((ma hoi) OR (mai hoi)). lieu ((va nam) or (va nay)) duoc ban thanh ca cua tre*.