Perhaps you should try some spelling variations:
"societal effective model" » "societal effects model", "social affective model", "societal effect model"
"social effect models" » "social effects models", "societal effect models", "special effect 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 ((("societal effective model") OR ("social effect models")))).
• Removing quotes may allow a broader search: (( social exact model ) or ((( societal effective model ) or ( social effect models )))).
• Adding a wildcard symbol may retrieve word variants: (("social exact model") or ((("societal effective model") or ("social effect models"))))*.