Perhaps you should try some spelling variations:
cua triet » su triet, va triet
ban thanh » ban hanh, ban hang
cua viet » ca viet, hoa viet, cua vat
hieu van » hieu va, thien van, lieu va
quoc ban » quoc bao, quoc lan, quoc quan
cam quoc » cac quoc, cao quoc, nam quoc
van cam » van nam, van lam, van cau
cua tre » cua te, cuu tre, dua tren
so sach » so sanh, bo sach, co sach
sach 2 » sach y
nang o » nang co, nang ho, nang ro
2 nang » v nang
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: so sach 2 nang o hoi. hieu van cam quoc ban thanh san ((cua tre) or (((cua triet) or (cua viet))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach 2 nang o hoi. hieu van cam quoc ban thanh san ((cua tre) OR (((cua triet) OR (cua viet)))).
• Adding a wildcard symbol may retrieve word variants: so sach 2 nang o hoi. hieu van cam quoc ban thanh san ((cua tre) or (((cua triet) or (cua viet))))*.