RT Journal Article SR Electronic T1 Incidence of Concussion Among Youth Football Players JF AAP Grand Rounds JO AAP Grand Rounds FD American Academy of Pediatrics SP 3 OP 3 DO 10.1542/gr.42-1-3 VO 42 IS 1 YR 2019 UL http://aapgrandrounds.aappublications.org/content/42/1/3.abstract AB