Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
nam thuc » nam thuoc, am thuc, nam thu
su sach » so sach
hanh di » hanh vi, hanh de, hang di
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
vu sach » vu bach, vu khach
v nang » va nang, vu nang, van nang
ve nam » he nam, va nam, le nam
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)) v nang ((x hoi) or (o hoi)). hieu ve nam thuc vat hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) v nang ((x hoi) OR (o hoi)). hieu ve nam thuc vat hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) v nang ((x hoi) or (o hoi)). hieu ve nam thuc vat hanh di cua tre*.