Perhaps you should try some spelling variations:
"societal effect model" » "societal effects model", "social effects model", "society effects model", "societal effect models", "societal effective model"
"special effects models" » "special effect models"
"social effect model" » "social effects model", "special effect model", "local effect model", "social effect models", "social effective model"
"social etas model" » "social etats model", "social eclas model", "social et model", "social keras model", "social gas model", "social das model"

Try widening your search to All Fields.

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 ("societal effect model"))) OR ("social etas model"))) OR ("special effects models")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"social effect model\") OR (\"societal effect model\"))) or (\"social etas model\"))) or (\"special effects models\"))".
• Removing quotes may allow a broader search: (((((( social effect model ) OR ( societal effect model ))) or ( social etas model ))) or ( special effects models )).
• Adding a wildcard symbol may retrieve word variants: (((((("social effect model") OR ("societal effect model"))) or ("social etas model"))) or ("special effects models"))*.