Perhaps you should try some spelling variations:
"social exact model" » "social effect model", "social etats model", "social et model", "social enxact model"
"social e model" » "social en model", "social e modelli"
"social de model" » "social pde model", "social ode model", "social de modele", "social de modelli"

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 de model"))))*.
• Removing quotes may allow a broader search: (( social exact model ) or ((( social e model ) or ( social de model ))))*.