Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
sach kem » hanh kem
nam thuc » nam thuoc, am thuc, nam thu
va thanh » gia thanh, ban thanh, va tinh
thanh di » thanh doi, thanh de, thanh do
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, o hoi, 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: su ((sach kem) or (sac ky)) nang ((x hoi) OR (x ho)). hieu van nam thuc va thanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach kem) OR (sac ky)) nang ((x hoi) OR (x ho)). hieu van nam thuc va thanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach kem) or (sac ky)) nang ((x hoi) OR (x ho)). hieu van nam thuc va thanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach kem) or (sac ky)) nang ((x hoi) OR (x ho)). hieu van nam thuc va thanh di cua tre*.