Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
van thanh » ban thanh, van tuan
vai cua » dai cua, hai cua, lai cua
van anh » tuan anh, van minh
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
ve bao » te bao, va bao
bao vo » bao ve, bao va, bao co
nang o » nang co, nang ho, nang ro
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) or (su sach)) ky nang o hoi. hieu ve bao vo ((van anh) OR (van thanh)) vai cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang o hoi. hieu ve bao vo ((van anh) OR (van thanh)) vai cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang o hoi. hieu ve bao vo ((van anh) OR (van thanh)) vai cua triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang o hoi. hieu ve bao vo ((van anh) OR (van thanh)) vai cua triet*.