BRIEFABSCHRIFT Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Dating: 22.07.1915
BRIEFABSCHRIFT Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Dating: 18.10.1915
BRIEFABSCHRIFT Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Dating: 26.10.1915
BRIEF OHNE UMSCHLAG Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Dating: 31.10.1915
BRIEFABSCHRIFT Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 10.01.1916
BRIEFABSCHRIFT Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Dating: 21.01.1916
BRIEF OHNE UMSCHLAG Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 01.04.1916
BRIEFABSCHRIFT Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Dating: 31.05.1916
BRIEFABSCHRIFT Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Dating: 29.07.1916
BRIEF OHNE UMSCHLAG Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 18.11.1915