Perhaps you should try some spelling variations:
van dung » van dong, xay dung, tin dung
van hanh » van thanh, ban hanh, van anh
su triet » su viet, su tien, ve triet
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac nuoc
cac dac » cac dan, cac dai, cac bac
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: su sach ((van dung) or (van ban)) xa hoi. hieu ve ((cac duc) OR (cac dac)) van hanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((van dung) OR (van ban)) xa hoi. hieu ve ((cac duc) OR (cac dac)) van hanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((van dung) or (van ban)) xa hoi. hieu ve ((cac duc) OR (cac dac)) van hanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: su sach ((van dung) or (van ban)) xa hoi. hieu ve ((cac duc) OR (cac dac)) van hanh vi su triet*.