Perhaps you should try some spelling variations:
"social effect model" » "social effects model", "societal effect model", "special effect model", "social effect models", "social effects models"
"social exact model" » "social et model", "social email model", "social era model"
"social etats model" » "social ethics model", "social etas model", "social rats model", "social beats 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 ("social etats model"))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"social exact model\") OR (\"social effect model\"))) or (\"social etats model\"))*".
• Removing quotes may allow a broader search: (((( social exact model ) OR ( social effect model ))) or ( social etats model ))*.