Double aortic arch. Johns Hopkins University, Cove Point Foundation website. Available at:
http://www.pted.org/?id=doubleaortic1. Updated May 16, 2011. Accessed July 19, 2013.
Vascular ring. Children’s Hospital Boston website. Available at:
http://www.childrenshospital.org/az/Site1942/mainpageS1942P0.html. Accessed July 19, 2013.
American Academy of Pediatrics
American Heart Association
Canadian Cardiovascular Society
Heart and Stroke Foundation of Canada