Perhaps you should try some spelling variations:
"social net model" » "social news model", "social na model", "social needs model"
"social set model" » "social seat model", "social asset model", "social ssl model"
"social self model" » "social self made", "social emf model", "social self modeling"

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 net model") OR ((("social set model") OR ("social self model"))))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"social net model\") or (((\"social set model\") OR (\"social self model\"))))*".
• Removing quotes may allow a broader search: (( social net model ) or ((( social set model ) OR ( social self model ))))*.