The attribution was advanced by Michael Jaffé. The ink number on the upper left is similar to those on the portraits of Cossiers's sons in the Pierpont Morgan Library (F. Stampfle, Rubens and Rembrandt in Their Century: Flemish and Dutch Drawings of the 17th Century from the Pierpont Morgan Library, New York, 1979, no. 34), the Lugt Collection (C. van Hasselt, Flemish Drawings of the Seventeenth Century from the Collection of Frits Lugt, Institut Néerlandais, New York and Paris, 1977, no. 34), British Museum (A.M. Hind, Catalogue of Drawings by Dutch and Flemish Artists, London, 1923, II, p. 98, no. 1, pl. XLIX), the van Regteren Altena Collection, Amsterdam (M.J. Giltay, Le Cabinet d'un Amateur, Dessins flamands et hollandais des XVI^e et XVII^e siècles d'une collection privée d'Amsterdam, Paris, 1976, no. 43, pl. 106) and a recently discovered addition to the group at Baskett and Day, An Exhibition of Old Master Drawings, 1987, no. 35, illustrated. The boy in this drawing might be a portrait of his son Cornelis, as the upturned nose and the prominent upper lip recall the drawing of him in the van Regteren Altena Collection