Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » thien van, lieu va, hieu ve
sach vu » sach va, sach tu, sach uu
hanh di » hanh vi, hanh de, hang di
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
vu nang » vuc nang, va nang, vu dang
tuc va » thuc va, truc va, tuc xa
nang o » nang co, nang ho, nang ro
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 vu nang o hoi. ((hieu van) OR (hieu va)) 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 vu nang o hoi. ((hieu van) OR (hieu va)) cam ((tuc va) or (duc va)) hanh di cua tre~".
• Adding a wildcard symbol may retrieve word variants: toc sach vu nang o hoi. ((hieu van) OR (hieu va)) cam ((tuc va) or (duc va)) hanh di cua tre*.