Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
nam thuc » nam thuoc, am thuc, nam thu
bang cau » hang cau, bang cac, nang cao
va thanh » gia thanh, va tinh, le thanh
tu sach » thu sach, su sach, te sach
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
ty bang » ty xang, te bang, ty hang
cam tu » cam thu, nam tu, dam tu

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 ty bang cau hoi. hieu ve ((cam tu) or (nam thuc)) ((va thanh) or (ban thanh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty bang cau hoi. hieu ve ((cam tu) OR (nam thuc)) ((va thanh) OR (ban thanh)) tai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ty bang cau hoi. hieu ve ((cam tu) or (nam thuc)) ((va thanh) or (ban thanh)) tai cua tre*.