He discovered that it had come from the same tree as Rembrandt 's '' Self-Portrait With a Hat '' ( 1633 ) , which is in the Louvre , as well as '' Portrait of Willem Burggraaff , '' also for 1633 , in the Staatliche Kunstsammlungen in Dresden , Germany , which has been attributed to the artist 's workshop , and a landscape in the Wallace Collection in London that is thought to be from 1640 and was painted by a student of Rembrandt .