Perhaps you should try some spelling variations:
thanh di » thanh doi, thanh de, thanh do
hieu van » hieu va, thien van, lieu va
van cam » van nam, van lam, van cau
thuc va » thuc vat, thuc dan, thuc day
di cua » dai cua, doi cua, de cua
tuc va » truc va, tuc xa, duc va
so sac » so sach, so dac
sac ky » cac ky, sai ky
cua te » cua tu
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sac ky nang ((o hoi) or (o hai)). hieu van cam ((tuc va) or (thuc va)) thanh di cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sac ky nang ((o hoi) OR (o hai)). hieu van cam ((tuc va) OR (thuc va)) thanh di cua te.
• Adding a wildcard symbol may retrieve word variants: so sac ky nang ((o hoi) or (o hai)). hieu van cam ((tuc va) or (thuc va)) thanh di cua te*.