WIA GC/1400 | Meyer, Richard to Warburg, Aby 24/03/1904 | does Warburg know the book by Karl Groos, 'Die Spiele der Menschen'? |
WIA GC/1941 | Strack, Max L. to Warburg, Aby 12/12/1905 | apologies to Mary Warburg; recommends child psychologist [Karl] Groos |
WIA GC/242 | Warburg, Aby to Groos, Karl 16/02/1918 | forwards offprints from Groos, sent to the late Robert Münzel; encloses the bookplate, made by... |
WIA GC/27804 | Warburg, Aby to Goldschmidt, Adolph 09/08/1903 | further to their conversation on Lehrter train station [Berlin], he explains the directions of... |
WIA GC/29066 | Groos, Karl to Warburg, Aby 22/02/1918 | thanks him for offprints and the beautiful [Robert Münzel] bookplate |