Perhaps you should try some spelling variations:
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
toc sach » hoc sach, doc sach, thuoc sach
hanh doi » thanh doi, hanh noi, hang doi
ban hanh » ban hang
doi cua » dai cua, hoi cua
xuc ban » duc ban, cuc ban, quoc ban
nam xuc » cam xuc, nam xua, nam thuc
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
o hoc » co hoc, mo hoc, so hoc

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: ((te sach) OR (toc sach)) ky nang o hoc. ((hieu van) OR (thien van)) nam xuc ban hanh doi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ky nang o hoc. ((hieu van) OR (thien van)) nam xuc ban hanh doi cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky nang o hoc. ((hieu van) OR (thien van)) nam xuc ban hanh doi cua tre*.