Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
hieu ve » hieu va, hieu van
sach ky » sac ky, sach ty, sach kem
nang o » nang co, nang ho, nang ro
ve cac » va cac, vien cac
bo van » vo van, so van, ho van
do van » dao van, vo van, so van
o hoi » co hoi, o hoc, o hai
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: thu ((sach ky) OR (sach y)) nang o hoi. hieu ve cac ((bo van) or (do van)) hanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sach y)) nang o hoi. hieu ve cac ((bo van) OR (do van)) hanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) OR (sach y)) nang o hoi. hieu ve cac ((bo van) or (do van)) hanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) OR (sach y)) nang o hoi. hieu ve cac ((bo van) or (do van)) hanh vi su triet*.