WIA GC/1907/35
Internationales Institut für Sozial-Bibliographie to Warburg, Aby 14/09/1907
thanks him for taking out a subscription to 'Kritische Blätter'; forwards the issues so far...
WIA GC/1907/375
Warburg, Aby to Internationales Institut für Sozial-Bibliographie 12/12/1907
his brother Felix M. Warburg pays a membership fee of M. 25.-, Warburg pays the fee of M. 15...
WIA GC/1912/66
Warburg, Aby to Beck, Hermann 17/12/1912
only catalogues dealing with sociology to be sent to him; regrets that they discontinued...