Berretta, Roberto, et al. “Tubal Ectopic Pregnancy: Our Experience from 2000 to 2013”. Acta Biomedica Atenei Parmensis, vol. 86, no. 2, Sept. 2015, pp. 176-80, https://mattioli1885journals.com/index.php/actabiomedica/article/view/3987.