Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
thanh di » thanh doi, thanh de, thanh do
sach ty » sach y, sach thu, xach tay
sach tu » sach thu, cach tu, sach uu
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
cau du » cau do, cac du, cau tu
du ban » dua ban, duc ban, du bao
di cua » dai cua, doi cua, de cua
x hoi » o hoi, x ho, 5 hoi

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 ty) or (sach tu)) nang ((x hoi) or (xa hoi)). hieu van cau du ban thanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ty) OR (sach tu)) nang ((x hoi) OR (xa hoi)). hieu van cau du ban thanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: thu ((sach ty) or (sach tu)) nang ((x hoi) or (xa hoi)). hieu van cau du ban thanh di cua tre*.