Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
su triet » su viet, su tien, ve triet
hieu va » lieu va, hieu qua
sac ky » cac ky, sai ky
cac so » cac bo, cac ho, cac o
cac co » cac cong
x hoi » xa hoi, o hoi, x ho
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: tu ((sach y) or (sac ky)) nang x hoi. hieu va ((cac so) OR (cac co)) van hanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach y) OR (sac ky)) nang x hoi. hieu va ((cac so) OR (cac co)) van hanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach y) or (sac ky)) nang x hoi. hieu va ((cac so) OR (cac co)) van hanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach y) or (sac ky)) nang x hoi. hieu va ((cac so) OR (cac co)) van hanh vi su triet*.