Perhaps you should try some spelling variations:
"special effect model" » "special effects model", "spectral effects model", "social effects model", "special effects models", "special effective model"
"special effect models" » "special effects models", "spectral effects models", "social effects models", "special effects modelss", "special effective models"
"social effect model" » "social effects model", "societal effect model", "focal effect model", "social effects models", "social effective model"
"social exact model" » "social etats model", "social et model", "social email model"
"local effect model" » "local effects model", "local effects models", "local effective model", "global effect model", "legal effect 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 exact model") OR ((("social effect model") OR ("local effect model"))))) OR ((("special effect model") OR ("special effect models")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"social exact model\") or (((\"social effect model\") OR (\"local effect model\"))))) or (((\"special effect model\") or (\"special effect models\"))))".
• Removing quotes may allow a broader search: (((( social exact model ) or ((( social effect model ) OR ( local effect model ))))) or ((( special effect model ) or ( special effect models )))).
• Adding a wildcard symbol may retrieve word variants: (((("social exact model") or ((("social effect model") OR ("local effect model"))))) or ((("special effect model") or ("special effect models"))))*.