Pellegrini, Gaia, et al. “Qualitative and Quantitative Analysis of Gingival Microvessels by Capillaroscopy in Healthy Subjects”. Italian Journal of Anatomy and Embryology, vol. 121, no. 1, Oct. 2017, p. 122, https://oajournals.fupress.net/index.php/ijae/article/view/2260.