Perhaps you should try some spelling variations:
"social effects model" » "special effects model", "social aspects model", "societal effects model", "local effects model", "social effects models"
"social effect model" » "societal effect model", "special effect model", "local effect model", "social effects models", "social effective model", "social object model"
"social effect models" » "societal effect models", "special effect models", "local effect models", "social effects modelss", "social effective models", "social object models"
"social exact model" » "social etats model", "social et model", "social email 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 ("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 (\"social effect models\"))) or (\"social effects model\"))))".
• Removing quotes may allow a broader search: (( social exact model ) or ((((( social 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 ("social effect models"))) or ("social effects model"))))*.