Grava, C., et al. “Isolated Congenital Heart Block in Undifferentiated Connective Tissue Disease and in Primary Sjögren’s Syndrome: A Clinical Study of 81 Pregnancies in 41 Patients”. Reumatismo, vol. 57, no. 3, Apr. 2005, pp. 180-6, doi:10.4081/reumatismo.2005.180.