Perhaps you should try some spelling variations:
"spectral effects model" » "special effects model", "sectoral effects model", "central effects model", "spectral effects models", "spectral effect models"
"special respect model" » "special aspects model", "special report model", "special request model", "special aspect model", "special respective model", "special respect de"
"special effect model" » "special effects model", "social effects model", "special event model", "special effect models", "special effects models", "special effective model"
"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 ((((("special effect model") OR ("spectral effects model"))) OR ("special respect model")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"social exact model\") or (((((\"special effect model\") OR (\"spectral effects model\"))) or (\"special respect model\"))))".
• Removing quotes may allow a broader search: (( social exact model ) or ((((( special effect model ) OR ( spectral effects model ))) or ( special respect model )))).
• Adding a wildcard symbol may retrieve word variants: (("social exact model") or ((((("special effect model") OR ("spectral effects model"))) or ("special respect model"))))*.