Perhaps you should try some spelling variations:
cac truc » cac tru, cac trung, sach truc
thanh vi » hanh vi, thanh va, thanh ve
su triet » su viet, su tien, ve triet
so sach » so sanh, bo sach, hoc sach
co sach » bo sach, cuon sach, hoc sach
hieu ve » hieu va, hieu van
xang o » lang o, tang o, dang o
o hoc » co hoc, mo hoc, so hoc
vi su » va su, ve su, ki su

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) or (co sach)) ty xang o hoc. hieu ve ((cac truc) OR (cau truc)) gia thanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (co sach)) ty xang o hoc. hieu ve ((cac truc) OR (cau truc)) gia thanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) or (co sach)) ty xang o hoc. hieu ve ((cac truc) OR (cau truc)) gia thanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (co sach)) ty xang o hoc. hieu ve ((cac truc) OR (cau truc)) gia thanh vi su triet*.