Perhaps you should try some spelling variations:
"social jetlag model" » "social eulag model", "social lag model", "social tag model", "social jelag model", "social actlag model", "social agentlag model"
"social jet model" » "social je model", "social act model", "social agent model", "social net model"
"social set model" » "social seat model", "social asset model", "social self model", "social net model"

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