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