Perhaps you should try some spelling variations:
thieu nien » thien nhien
bieu hien » dieu hien, dieu khien, bien phien
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
bai va » mai va, ban va, dai va
vi cua » vai cua, di cua
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: tu sach ky nang ((x hoi) OR (o hoi)). ((thieu nien) or (bieu hien)) cac bai va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (o hoi)). ((thieu nien) OR (bieu hien)) cac bai va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) OR (o hoi)). ((thieu nien) or (bieu hien)) cac bai va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) OR (o hoi)). ((thieu nien) or (bieu hien)) cac bai va hanh vi cua tre*.