WIA GC/1906/277 | Warburg, Aby to Guba, Anton 29/09/1906 | his son had not paid Mr. [Walter] Voltmer, the painting teacher, although he maintained he had... |
WIA GC/1906/278 | Warburg, Aby to Guba, Anton 09/10/1906 | on his son's behaviour; Rudolf Guba did not pay the teacher, but turned to Warburg to borrow... |