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