BRIEF OHNE UMSCHLAG Kemna, Adolf; Vyve, B. van Author: Kemna, Adolf; Vyve, B. van Recipient: Haeckel, Ernst Corporation: Réunion Scientifique d'Anvers Dating: 14.02.1894
BRIEF OHNE UMSCHLAG Marchal, Edmond Author: Marchal, Edmond Recipient: Haeckel, Ernst Corporation: Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique Dating: 05.05.1904
TELEGRAMM Sethe-Seyberth, Louise; Sethe, Walter Author: Sethe-Seyberth, Louise; Sethe, Walter Recipient: Haeckel, Ernst Dating: 15.02.1914
BRIEF OHNE UMSCHLAG Beneden, Eduard van Author: Beneden, Eduard van Recipient: Haeckel, Ernst Dating: 03.01.1891
BRIEF OHNE UMSCHLAG Greeff, Richard Author: Greeff, Richard Recipient: Haeckel, Ernst Dating: 27.08.1866
