BRIEF [O.A.] Grün, Robb... S... Author: Grün, Robb... S... Recipient: Haeckel, Ernst Dating: 09.01.1893
BRIEF [O.A.] Lampert, Kurt Author: Lampert, Kurt Recipient: Haeckel, Ernst Corporation: Königliches Naturalien-Cabinett Dating: 19.04.1893