Comparable drawings by Fontana are in the Uffizi (M. Di Giampaolo, Disegni Emiliani del Rinascimento, Bologna, 1989, no. 89), at Windsor Castle (A.E. Popham and J. Wilde, The Italian Drawings of the XV and XVI Centuries in the Collection of his Majesty the King at Windsor Castle, London, 1949, no. 1066, pl. 85, as Taddeo Zuccaro), in the Louvre, (C. Monbeig-Goguel, Vasari et son temps, Paris, 1972, no. 316) and with with Pandora Fine Arts, 2001, no. 3.
We are grateful to Dr. Florian Härb for suggesting the attribution.