The attribution is based on comparison with similar drawings attributed to the artist in the Rijksprentenkabinet, Amsterdam (K.G. Boon, Netherlandish Drawings of the Fifteenth and Sixteenth Centuries in the Rijksmuseum, The Hague, 1978, I, pp. 141-3, nos. 392 and 398, II, illustrated pp. 150-1). As Dr. H.-U. Beck has kindly pointed out, no. 398 also comes from the Ploos van Amstel collection, lot B33 (Dfl. 1.10 to Yver). This would explain the same handwriting on the drawings.