Perhaps you should try some spelling variations:
quoc ban » quoc bao, quoc lan, quoc quan
tu sach » thu sach, su sach, te sach
cac ban » cac dan, cac van, can ban
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
y hang » ly hang, ty hang, yu hang
co hai » co dai, co hoi, so hai
anh de » hanh de, anh d, anh ve
de cua » le cua, te cua, dieu cua
va cam » va cham, va cac, va cao
o hai » so hai, o lai, _ hai

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 y hang ((o hai) or (co hai)). hieu va cam ((cac ban) or (quoc ban)) anh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y hang ((o hai) OR (co hai)). hieu va cam ((cac ban) OR (quoc ban)) anh de cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y hang ((o hai) or (co hai)). hieu va cam ((cac ban) or (quoc ban)) anh de cua tre*.