W.A. van Wamel, and P.E. Zwart. “The Structural Geology and Basin Development of the Romagnan-Umbrian Zone (Upper Savio- and Upper Bidente Valleys, N. Italy)”. Netherlands Journal of Geosciences, Jan. 1990, pp. 53-68, https://njgjournal.nl/index.php/njg/article/view/12852.