Mihali, Klevis, Birgit Markus, Bernhard Schieffer, Marcus Bauer, and Julian Kreutz. “Thinking Outside the Box: Case Report of a Rare Quadricuspid Aortic Valve As an Underrecognized Cause of Heart Failure and Atrial Fibrillation”. Journal of Medical Cases 16, no. 8 (August 22, 2025): 277–281. Accessed October 28, 2025. https://jmc.elmerpub.com/index.php/jmc/article/view/5153.