Perhaps you should try some spelling variations:
"social needs model" » "special needs model", "social norms model", "social needs more"
"social news model" » "social views model", "social norms model", "social newns model", "social news modul"
"social net model" » "social na model", "social net models"

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 net model") OR ((("social news model") OR ("social needs model")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"social net model\") or (((\"social news model\") OR (\"social needs model\"))))".
• Removing quotes may allow a broader search: (( social net model ) or ((( social news model ) OR ( social needs model )))).
• Adding a wildcard symbol may retrieve word variants: (("social net model") or ((("social news model") OR ("social needs model"))))*.