Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thanh de » hanh de, thanh ve, thanh do
thanh di » thanh doi, thanh do, thanh dinh
luc gia » luoc gia, duc gia, quoc gia
van coc » van hoc, van loc, van co
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty hang, ly nang
cua tre » cua te, cuu tre, cua triet
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((ty nang) or (ty xang)) x hoi. hieu van coc luc gia ((thanh di) OR (thanh de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (ty xang)) x hoi. hieu van coc luc gia ((thanh di) OR (thanh de)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty nang) or (ty xang)) x hoi. hieu van coc luc gia ((thanh di) OR (thanh de)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) or (ty xang)) x hoi. hieu van coc luc gia ((thanh di) OR (thanh de)) cua tre*.