BRIEF OHNE UMSCHLAG Amin, Giovanni Author: Amin, Giovanni Recipient: Haeckel, Ernst Corporation: Comitato Universitario Centrale Sottoscizione Internazionale per un Monumento a Giordano Bruno Dating: 19.04.1889
POSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Carneri, Bartholomäus von Dating: 31.03.1889
TELEGRAMM Krauseneck, Heinrich Author: Krauseneck, Heinrich Recipient: Haeckel, Ernst Dating: 12.12.1889
Krauseneck, Gustav Adolf; Krauseneck, Olga Author: Krauseneck, Gustav Adolf; Krauseneck, Olga Recipient: Haeckel, Ernst Dating: 12.12.1889