RT Journal Article SR Electronic T1 Concussion in youth ice hockey: It's time to break the cycle JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP cmaj.110282 DO 10.1503/cmaj.110282 A1 L. Syd M. Johnson YR 2011 UL http://www.cmaj.ca/content/early/2011/04/18/cmaj.110282.abstract AB