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