Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh di » thanh doi, thanh de, thanh do
hieu van » hieu va, thien van, lieu va
dat ban » bat ban, da ban, day ban
cac dat » cac dan, cai dat, cac dai
van cac » van hac, van cau, van bac
mai hoi » mai khoi, dai hoi, lai hoi
sach ky » sach y, sach ty, sach kem
ma hoi » xa hoi, ma hoa, me hoi
sac ky » cac ky, sai ky
di cua » dai cua, doi cua, de 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 (sac ky)) nang ((ma hoi) or (mai hoi)). hieu van cac dat ban thanh di cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sac ky)) nang ((ma hoi) OR (mai hoi)). hieu van cac dat ban thanh di cua vat.
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sac ky)) nang ((ma hoi) or (mai hoi)). hieu van cac dat ban thanh di cua vat*.