Perhaps you should try some spelling variations:
"social beats model" » "social beasts model", "social bots model", "social etats model", "social seats model", "social nets model"
"social rates model" » "social rate model", "social states model", "social rules model", "social rates models", "social bates model"
"social roles model" » "social role model", "social robots model", "social robot model", "social rules model", "social role models"

Try widening your search to All Fields.

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 beats model") OR ((("social rates model") OR ("social roles model")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"social beats model\") or (((\"social rates model\") OR (\"social roles model\"))))".
• Removing quotes may allow a broader search: (( social beats model ) or ((( social rates model ) OR ( social roles model )))).
• Adding a wildcard symbol may retrieve word variants: (("social beats model") or ((("social rates model") OR ("social roles model"))))*.