Perhaps you should try some spelling variations:
thanh dan » thanh van, thanh dat, thanh dam
thu sach » tu sach, thuat sach, thuoc sach
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
tuc gia » tac gia, duc gia, toc gia
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach y nang ((x hoi) or (o hoi)). hieu va cac tuc gia ((thanh dan) OR (thanh san)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((x hoi) OR (o hoi)). hieu va cac tuc gia ((thanh dan) OR (thanh san)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((x hoi) or (o hoi)). hieu va cac tuc gia ((thanh dan) OR (thanh san)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((x hoi) or (o hoi)). hieu va cac tuc gia ((thanh dan) OR (thanh san)) cua tre*.