Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
vat dao » va dao, van dao, hat dao
vai cua » dai cua, hai cua, lai cua
vat da » vat va, vat de
o hoi » co hoi, o hoc, o hai
ve am » va am
thuc » thu

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 ky nang ((o hoi) OR (x ho)). hieu ve am thuc ((vat dao) OR (vat da)) vai cua triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoi) or (x ho)). hieu ve am thuc ((vat dao) OR (vat da)) vai cua triet~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (x ho)). hieu ve am thuc ((vat dao) OR (vat da)) vai cua triet*.