WIA GC/10372 | Warburg, Aby to Robinow, Richard 27/06/1906 | [Walter] Voltmer has agreed to teach Rudolf Guba for three months before Guba starts his training... |
WIA GC/10441 | Warburg, Aby to Voltmer, Walter 27/09/1906 | Warburg is still waiting for a reply from Voltmer re painting lessons for [Rudolf] Guba |
WIA GC/10442 | Warburg, Aby to Voltmer, Walter 29/09/1906 | thanks him for his letter and explanation; informs him of the monies raised for Rudolf Guba; is... |
WIA GC/10443 | 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/1638 | Guba, Rudolf to Warburg, Aby 28/08/1905 | asks for an appointment; [Walter] Voltmer will have sent a reference to Warburg in the meantime |