BRIEF OHNE UMSCHLAG Recipient: Gruyter, Walter de Corporation: Dodd, Mead and Company Publishers Dating: 27.12.1915
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Gruyter, Walter de Dating: 28.07.1916
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Gruyter, Walter de Dating: 04.08.1918