Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
bao duc » dao duc, bao luc, cao duc
hang di » hang doi, hang vi, hang dien
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
co hoi » co hoc, co loi
va bao » va bai
o hoi » o hoc, o hai, o hoa

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 ((o hoi) or (co hoi)). lieu va bao duc va ((hanh vi) or (hang di)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((o hoi) OR (co hoi)). lieu va bao duc va ((hanh vi) OR (hang di)) cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((o hoi) or (co hoi)). lieu va bao duc va ((hanh vi) or (hang di)) cua tre*.