RT Journal Article SR Electronic T1 Effects of repeated mild head impacts in contact sportsAbout concussion JF Neurology JO Neurology FD Lippincott Williams & Wilkins SP e140 OP e142 DO 10.1212/WNL.0b013e31825bc685 VO 78 IS 22 A1 Clark, Derek YR 2012 UL http://n.neurology.org/content/78/22/e140.abstract AB