Perhaps you should try some spelling variations:
"societal effect model" » "societal effects model", "social effects model", "society effects model", "societal effect models", "societal effects models"
"social effect model" » "social effects model", "special effect model", "local effect model", "social effect models", "social effects models"
"social net model" » "social news model", "social na model", "social needs model", "social nset model", "social njet model", "social net modele"
"social et model" » "social en model", "social e model", "social etats model", "social set model", "social jet model", "social et modele"

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