BRIEF OHNE UMSCHLAG Strasburger, Eduard Author: Strasburger, Eduard Recipient: Haeckel, Ernst Dating: 19.03.1884
BRIEF OHNE UMSCHLAG Strasburger, Eduard Author: Strasburger, Eduard Recipient: Haeckel, Ernst Dating: 08.06.1884
TELEGRAMM Strasburger, Eduard Author: Strasburger, Eduard Recipient: Haeckel, Ernst Dating: 03.05.1884