Perhaps you should try some spelling variations:
qua cham » qua hai, qua cac, va cham
hai cua » thai cua, dai cua, hoi cua
anh hai » lanh hai, manh hai, anh thai
cuu ban » cuu van, cua ban, cuu san
cuc ban » cua ban, cac ban, duc ban
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet

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 ((nang x) or (nang ma)) hoi. hieu qua cham ((cuc ban) OR (cuu ban)) anh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang x) OR (nang ma)) hoi. hieu qua cham ((cuc ban) OR (cuu ban)) anh hai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang x) or (nang ma)) hoi. hieu qua cham ((cuc ban) OR (cuu ban)) anh hai cua tre*".