Perhaps you should try some spelling variations:
giai duc » giao duc, gia duc, giac duoc
giap duc » giao duc, gia duc, giac duoc
van hanh » van thanh, ban hanh, van anh
sach le » sach de, sach lo, sach kem
cach le » cach de, cac le, cach ben
xay hoi » xa hoi, tay hoi, cay phoi
vi va » vi van, vai va, vu va
thiet » thieu

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 le) or (cach le)) van xay hoi. hieu qua ((giai duc) OR (giap duc)) van hanh vi va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach le) OR (cach le)) van xay hoi. hieu qua ((giai duc) OR (giap duc)) van hanh vi va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach le) or (cach le)) van xay hoi. hieu qua ((giai duc) OR (giap duc)) van hanh vi va thiet".
• Adding a wildcard symbol may retrieve word variants: su ((sach le) or (cach le)) van xay hoi. hieu qua ((giai duc) OR (giap duc)) van hanh vi va thiet*.