Perhaps you should try some spelling variations:
social jet » social je, social act, social jetlag
social lag » social law, social la, social lab
jet model » net model, set model
lag model » lag models, bag model, bag models

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 lag model )).
• Adding a wildcard symbol may retrieve word variants: (( social jet model ) or ( social lag model ))*.