Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
tu sach » thu sach, su sach, te sach
hieu va » hieu qua
va vanh » va van, va danh, va hanh
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
co hoi » co hoc, co loi
soc va » hoc va, loc va, doc va
o hoi » o hoc, o hai, o hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((o hoi) OR (co hoi)). ((hieu va) OR (lieu va)) cham soc va vanh dai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((o hoi) or (co hoi)). ((hieu va) OR (lieu va)) cham soc va vanh dai cua tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((o hoi) or (co hoi)). ((hieu va) OR (lieu va)) cham soc va vanh dai cua tre*.