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