Perhaps you should try some spelling variations:
hanh duoc » hanh thuoc, nganh duoc, doanh duoc
ban hanh » ban hang
duoc cua » duoc sua, nuoc cua, doc cua
sach ty » sach tu, sach thu, xach tay
hieu va » lieu va, hieu qua
cam duc » cam xuc, cao duc, pham duc
duc ban » duc tan, duc van, dua ban
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
va cam » va cham, va cac, va cao
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 va cam duc ban hanh duoc 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 va cam duc ban hanh duoc cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach y)) nang o hai. hieu va cam duc ban hanh duoc cua tre*.