Portrait of a Sitting Boy, 1900s, Oil on Cardboard

see Lexikon der Düsseldorfer Malerschule,Kunstmuseum Düsseldorf, Bruckmann Verlag Munich 1998, vol. 3 pp. 58-61, dimensions with frame This piece has an attribution mark,
I am sure that it is completely authentic and take full responsibility for any authenticity
issues arising from misattribution