Perhaps you should try some spelling variations:
social effect » social effects, societal effect, special effect
social exact » social etats, social et, social email
etats model » rats model, beats model, hats model
keras model » keras models
etas model » gas model, das model, ras 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) OR (social effect)) model ) OR ( social ((etats model) OR (((etas model) OR (keras model)))) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((social exact) or (social effect)) model ) or ( social ((etats model) or (((etas model) OR (keras model)))) ))".
• Adding a wildcard symbol may retrieve word variants: (( ((social exact) or (social effect)) model ) or ( social ((etats model) or (((etas model) OR (keras model)))) ))*.