Perhaps you should try some spelling variations:
societal effect » societal effects, social effects, society effects
effect model » effect models, effects model, effects models
etats model » etas model, beats model, hats model
rats model » rat model, rate model, ratio 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 ((etats model) OR (rats model)) ) OR ( societal effect model )).
• Adding a wildcard symbol may retrieve word variants: (( social ((etats model) or (rats model)) ) or ( societal effect model ))*.