Ninety-three hearts > or = 90 years of age.

MLA

Roberts, W. C. “Ninety-Three Hearts > or = 90 Years of Age.” The American Journal of Cardiology, vol. 71, no. 7, Mar. 1993, pp. 599–602. EBSCOhost, https://doi.org/10.1016/0002-9149(93)90519-i.

APA

Roberts, W. C. (1993). Ninety-three hearts > or = 90 years of age. The American Journal of Cardiology, 71(7), 599–602. https://doi.org/10.1016/0002-9149(93)90519-i

Chicago

Roberts, W C. 1993. “Ninety-Three Hearts > or = 90 Years of Age.” The American Journal of Cardiology 71 (7): 599–602. doi:10.1016/0002-9149(93)90519-i.