Perhaps you should try some spelling variations:
"social effective model" » "social affective model", "special effective model", "local effective model", "social effects model", "social effectsive model", "societal effective model"
"special effect models" » "special effects models", "spectral effects models", "special respect models", "special effects modelss", "special object models"
"social effect model" » "social effects model", "societal effect model", "local effect model", "social effects models", "social object model"
"social exact model" » "social etats model", "social et model", "social email 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 ("social effective 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 (\"social effective model\"))))) or (\"special effect models\"))".
• Removing quotes may allow a broader search: (((( social exact model ) or ((( social effect model ) OR ( social effective model ))))) or ( special effect models )).
• Adding a wildcard symbol may retrieve word variants: (((("social exact model") or ((("social effect model") OR ("social effective model"))))) or ("special effect models"))*.