Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
vu sach » vu bach, su sach, vu khach
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
hieu ve » hieu van
vu nang » vuc nang, va nang, vu dang
cua tre » cua te, cuu tre, cua triet
v nang » va nang, van nang, voi nang
vi cua » vai cua, di cua
o hoi » co hoi, o hoc, o hai

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

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