Perhaps you should try some spelling variations:
societal effect » societal effects, social effects, society effects
special effect » special effects, spectral effects, social effects
social exact » social effect, social etats, social et
effect model » effect models, effects model, effects models

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 effect model )).
• Adding a wildcard symbol may retrieve word variants: (((( social exact model ) or ( societal effect model ))) or ( special effect model ))*.