Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
thanh di » thanh doi, thanh de, thanh do
ve pham » vi pham, v pham, ve phan
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
ty nang » ky nang, ty xang, ty hang
duy va » duy vat, duy van, duy v
di cua » dai cua, doi cua, de cua
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, 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 ty nang ((o hoi) OR (o hai)). hieu ve pham ((duy va) OR (day va)) thanh di cua triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((o hoi) or (o hai)). hieu ve pham ((duy va) OR (day va)) thanh di cua triet~".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((o hoi) or (o hai)). hieu ve pham ((duy va) OR (day va)) thanh di cua triet*.