Perhaps you should try some spelling variations:
ban hanh » ban hang
hanh doc » hanh duoc, nhanh doc, anh doc
sach ty » sach tu, sach thu, xach tay
qua cam » qua cham, qua cac, qua ca
cam duc » cam xuc, cao duc, pham duc
duc ban » duc tan, duc van, dua ban
doc cua » hoc cua, doi cua, do cua
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
o hai » co hai, so hai, o lai

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) or (sach y)) nang o hai. hieu qua cam duc ban hanh doc cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach y)) nang o hai. hieu qua cam duc ban hanh doc cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach y)) nang o hai. hieu qua cam duc ban hanh doc cua tre*.