BRIEF [O.A.] Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Dating: 16.10.1915
BRIEF OHNE UMSCHLAG Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 18.11.1915
BRIEF OHNE UMSCHLAG Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 29.10.1915
BRIEF OHNE UMSCHLAG Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 18.10.1915
BRIEF OHNE UMSCHLAG Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 26.10.1915
BRIEFENTWURF Gruyter, Walter de Author: Gruyter, Walter de Recipient: N. N. Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 31.01.1915
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