Perhaps you should try some spelling variations:
thanh dai » thanh tai, thanh dat, thanh oai
cua triet » cua viet, su triet
thanh hai » thanh phan, thanh hoa, thanh san
va triet » va thiet, va trien, ve triet
hieu van » hieu va, thien van, lieu va
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
sach ky » sac ky, sach y, sach ty
so sach » so sanh, bo sach, co sach
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: so sach ky nang o hoi. hieu van cau duc va ((thanh dai) or (thanh hai)) ((cua triet) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang o hoi. hieu van cau duc va ((thanh dai) OR (thanh hai)) ((cua triet) OR (va triet)).
• Adding a wildcard symbol may retrieve word variants: so sach ky nang o hoi. hieu van cau duc va ((thanh dai) or (thanh hai)) ((cua triet) or (va triet))*.