Perhaps you should try some spelling variations:
ban thanh » ban hang
chau doc » chat doc, cau do, phau hoc
ban hanh » ban hang
cua tre » cua te, cuu tre, cua triet
ve chau » ve cau, ve chat, le chau
hieu ve » hieu va, hieu van
may hoi » may thoi, tay hoi, mai hoi
sach ty » sach y, sach tu, sach thu
sac ky » cac ky, sai ky
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: te ((sac ky) or (sach ty)) mang may hoi. hieu ve chau doc ((ban thanh) or (ban hanh)) va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sac ky) OR (sach ty)) mang may hoi. hieu ve chau doc ((ban thanh) OR (ban hanh)) va cua tre.
• Adding a wildcard symbol may retrieve word variants: te ((sac ky) or (sach ty)) mang may hoi. hieu ve chau doc ((ban thanh) or (ban hanh)) va cua tre*.