Jha, Abhijeet K., et al. “Periumbilical Perforating Pseudoxanthoma Elasticum: A Rare Case Report”. Dermatology Practical & Conceptual, vol. 8, no. 1, Apr. 2018, https://dpcj.org/index.php/dpc/article/view/dermatol-pract-concept-articleid-dp0802a02.