Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
su sach » so sach
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
vu nang » vuc nang, va nang, vu dang
vu sach » vu bach, vu khach
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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) or (vu sach)) vu nang ((x hoi) or (o hoi)). hieu van nam thuc van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) vu nang ((x hoi) OR (o hoi)). hieu van nam thuc van hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) vu nang ((x hoi) or (o hoi)). hieu van nam thuc van hanh di cua tre*.