Perhaps you should try some spelling variations:
"social network" » "social networks", "social netyork"
"social worker" » "social workers", "social world", "social market", "social workser", "social yorker"
"social work" » "social works", "social york"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("social network") OR ("social work"))) OR ("social worker")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"social network\") OR (\"social work\"))) or (\"social worker\"))".
• Removing quotes may allow a broader search: (((( social network ) OR ( social work ))) or ( social worker )).
• Adding a wildcard symbol may retrieve word variants: (((("social network") OR ("social work"))) or ("social worker"))*.