Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh va » thanh van, hanh va, thanh ha
cac lop » cac hop, cac loai
sach ky » sac ky, sach y, sach kem
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
lang xa » lang ha, dang xay, lang van
sach ty » sach y, sach tu, sach thu
cac lo » cac co, cac bo, cac ho
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) or (sach ty)) lang xa hoi. hieu ve ((cac lo) OR (cac lop)) ban thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sach ty)) lang xa hoi. hieu ve ((cac lo) OR (cac lop)) ban thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) or (sach ty)) lang xa hoi. hieu ve ((cac lo) OR (cac lop)) ban thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sach ty)) lang xa hoi. hieu ve ((cac lo) OR (cac lop)) ban thanh va cua tre*.