Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh dat, thanh oai
cua triet » cua viet, va triet
thanh tai » thanh hai, thanh toan, doanh tai
su triet » su viet, su tien, 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
tu sach » thu sach, su sach, te 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: tu sach ky nang o hoi. hieu van cau duc va ((thanh dai) OR (thanh tai)) ((cua triet) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hoi. hieu van cau duc va ((thanh dai) OR (thanh tai)) ((cua triet) OR (su triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang o hoi. hieu van cau duc va ((thanh dai) OR (thanh tai)) ((cua triet) or (su triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang o hoi. hieu van cau duc va ((thanh dai) OR (thanh tai)) ((cua triet) or (su triet))*.