Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
su sach » so sach, vu sach
hai cua » thai cua, dai cua, hoi cua
duc ban » duc van, dua ban, duc man
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
tang ma » tang van
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((tang ma) or (mang may)) hoi. hieu ve cam ((duc ban) OR (duc tan)) thanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((tang ma) OR (mang may)) hoi. hieu ve cam ((duc ban) OR (duc tan)) thanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((tang ma) or (mang may)) hoi. hieu ve cam ((duc ban) OR (duc tan)) thanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((tang ma) or (mang may)) hoi. hieu ve cam ((duc ban) OR (duc tan)) thanh hai cua tre*.