Perhaps you should try some spelling variations:
"social needs model" » "special needs model", "social norms model", "social needs more"
"social net model" » "social news model", "social na model"
"social da model" » "social de model", "social data model", "social del model", "social dea model", "social lda model", "social dna model"

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