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