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
cua tre » cua te, cua triet, dua tren
dau ban » dau bang, da ban, dau bao
cac dau » cac dan, cac du, cac dai
van cac » van hac, van cau, van bac
sach ty » sach y, sach thu, xach tay
sach tu » sach thu, cach tu, sach uu
cuu tre » cau tren, cau treo
x hoi » xa hoi, o hoi, x ho

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