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 etats model" » "social ethics model", "social etas model", "social rats model", "social beats model", "social enats model", "social eats model"
"social et model" » "social en model", "social e model", "social net model", "social set model", "social jet 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 ((("social et model") OR ("social etats model")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"social effect model\") or (((\"social et model\") OR (\"social etats model\"))))".
• Removing quotes may allow a broader search: (( social effect model ) or ((( social et model ) OR ( social etats model )))).
• Adding a wildcard symbol may retrieve word variants: (("social effect model") or ((("social et model") OR ("social etats model"))))*.