Perhaps you should try some spelling variations:
"societal effect model" » "societal effects model", "social effects model", "society effects model", "societal effect models", "societal effects models"
"special respect model" » "special aspects model", "special report model", "special effect model", "special aspect model", "special respective model", "special respect de"
"social exact model" » "social effect model", "social etats model", "social et model"

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 respect model")))).
• Removing quotes may allow a broader search: (( social exact model ) or ((( societal effect model ) or ( special respect model )))).
• Adding a wildcard symbol may retrieve word variants: (("social exact model") or ((("societal effect model") or ("special respect model"))))*.