Perhaps you should try some spelling variations:
"social exact model" » "social effect model", "social etats model", "social et model", "social enxact model"
"social bots model" » "social robots model", "social robot model", "social cots model", "social potts model", "social costs model"
"social e model" » "social en model", "social e modelli"

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

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