CE, H., SY, H., RH, A., & MJ, E. (1990). Variations within the fibrous skeleton and ventricular outflow tracts in tetralogy of Fallot. The Annals of thoracic surgery, 50(3), 450. https://doi.org/10.1016/0003-4975(90)90494-q
Chicago Style (17th ed.) CitationCE, Howell, Ho SY, Anderson RH, and Elliott MJ. "Variations Within the Fibrous Skeleton and Ventricular Outflow Tracts in Tetralogy of Fallot." The Annals of Thoracic Surgery 50, no. 3 (1990): 450. https://doi.org/10.1016/0003-4975(90)90494-q.
MLA (9th ed.) CitationCE, Howell, et al. "Variations Within the Fibrous Skeleton and Ventricular Outflow Tracts in Tetralogy of Fallot." The Annals of Thoracic Surgery, vol. 50, no. 3, 1990, p. 450, https://doi.org/10.1016/0003-4975(90)90494-q.
Warning: These citations may not always be 100% accurate.