Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
qua pham » quan pham, quy pham, qua cham
thanh ha » thanh hoa, thanh hai, nhanh ha
sach ky » sach y, sach ty, sach kem
duc ban » duc tan, duc van, dua ban
cua tre » cuu tre, cua triet, dua tren
sac ky » cac ky, sai ky
cua te » cua tu
x hoi » xa hoi, o hoi, x ho

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sac ky)) nang x hoi. hieu qua pham duc ban thanh ha ((cua tre) OR (cua te))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sac ky)) nang x hoi. hieu qua pham duc ban thanh ha ((cua tre) or (cua te))~".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) OR (sac ky)) nang x hoi. hieu qua pham duc ban thanh ha ((cua tre) or (cua te))*.