WIA GC/3749 | Eijkman, Pieter Hendrik and Horrix, Paul to Warburg, Aby 06/05/1910 | their office collects data on international projects of every description; they invite Warburg to... |
WIA GC/3751 | Warburg, Aby to Eijkman, Pieter Hendrik and Horrix, Paul 10/05/1910 | since the organisation has changed its byelaws and the new version has not yet appeared in print... |
WIA GC/3752 | Eijkman, Pieter Hendrik and Horrix, Paul to Warburg, Aby 13/05/1910 | acknowledge receipt of his letter |