Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
tu nong » tu dong, tu cong, tu tong
tu nang » tru nang, tu nano, tu lang
van cam » van nam, van lam, van cau
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa
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: toc sach ((tu nang) OR (tu nong)) o hoi. hieu van cam ((tuc va) OR (duc va)) hanh vi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((tu nang) OR (tu nong)) o hoi. hieu van cam ((tuc va) or (duc va)) hanh vi cua tre~".
• Adding a wildcard symbol may retrieve word variants: toc sach ((tu nang) OR (tu nong)) o hoi. hieu van cam ((tuc va) or (duc va)) hanh vi cua tre*.