Perhaps you should try some spelling variations:
"social exact model" » "social effect model", "social etats model", "social et model", "social enxact model"
"social jet model" » "social je model", "social act model", "social jetlag model", "social net model", "social set model"
"social e model" » "social en model", "social e modelli"

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 e model") OR ("social jet model")))).
• Removing quotes may allow a broader search: (( social exact model ) or ((( social e model ) or ( social jet model )))).
• Adding a wildcard symbol may retrieve word variants: (("social exact model") or ((("social e model") or ("social jet model"))))*.