Perhaps you should try some spelling variations:
kelly's criterion » kelly criterion, weyl's criterion, levy's criterion
concerns criteria » cancer criteria, concept criteria, contests criteria
pde's criteria » ideas criteria, peers criteria, models criteria

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: (( kelly's criterion ) OR ((( pde's criteria ) OR ( concerns criteria )))).
• Adding a wildcard symbol may retrieve word variants: (( kelly's criterion ) or ((( pde's criteria ) or ( concerns criteria ))))*.