Perhaps you should try some spelling variations:
thanh hoai » thanh hoa, thanh hai, thanh oai
hoai cua » hoi cua, hoa cua, hai cua
sach thu » sach thue, sach thieu, sach tham
nang mai » nang ma, nang tai, lang mai
qua ban » cua ban, qua quan
dua ban » dia ban, cua ban, mua ban
va cham » va chat, va tham
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
mai hoi » mai khoi, dai hoi, lai hoi
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 ky) or (sach thu)) nang mai hoi. hieu va cham ((dua ban) OR (qua ban)) thanh hoai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach thu)) nang mai hoi. hieu va cham ((dua ban) OR (qua ban)) thanh hoai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sach thu)) nang mai hoi. hieu va cham ((dua ban) OR (qua ban)) thanh hoai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sach thu)) nang mai hoi. hieu va cham ((dua ban) OR (qua ban)) thanh hoai cua tre*.