Perhaps you should try some spelling variations:
"special respect model" » "special aspects model", "special report model", "special request model", "special aspect model", "special respective model", "special respect de"
"social effect model" » "social effects model", "societal effect model", "special effect model", "social effect models", "social effects models"
"social exact model" » "social etats model", "social et model", "social email model"

You may be able to get more results by adjusting your search query.

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