Perhaps you should try some spelling variations:
khanh ban » khanh van, thanh ban, khanh luan
van khanh » van thanh, van hanh, van anh
toc sach » hoc sach, doc sach, thuoc sach
nuoc van » nuoc va, nuoc san, luoc van
hac nuoc » hoc nuoc, cac nuoc, phap nuoc
hieu van » hieu va, thien van, lieu va
ban cua » ban quan
van hac » van hoc, van ha, van hai
cua tre » cua te, cuu tre, cua triet
co hoi » co hoc, co loi
y nang » ky nang, ly nang, v nang
o hai » co hai, so hai, o lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) y nang ((co hoi) or (o hai)). hieu van hac nuoc van khanh ban cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) y nang ((co hoi) OR (o hai)). hieu van hac nuoc van khanh ban cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) y nang ((co hoi) or (o hai)). hieu van hac nuoc van khanh ban cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) y nang ((co hoi) or (o hai)). hieu van hac nuoc van khanh ban cua tre*.