Perhaps you should try some spelling variations:
"social effects model" » "special effects model", "social aspects model", "societal effects model", "focal effects model", "social effects models"
"social effect model" » "societal effect model", "special effect model", "focal effect model", "social effects models", "social effective model", "social object model"
"social effect models" » "societal effect models", "special effect models", "focal effect models", "social effects modelss", "social effective models", "social object models"
"social exact model" » "social etats model", "social et model", "social email model"
"local effect model" » "local effects models", "local effective model", "local object model", "local effects model", "global effect model", "legal effect model"

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