BRIEF OHNE UMSCHLAG Schumacher, Hermann Albert Author: Schumacher, Hermann Albert Recipient: Haeckel, Ernst Corporation: Kaiserlich Deutsches General-Consulat, New York Dating: 19.07.1879
BRIEF OHNE UMSCHLAG Schumacher, Hermann Albert Author: Schumacher, Hermann Albert Recipient: Haeckel, Ernst Corporation: Kaiserlich Deutsches General-Consulat, New York Dating: 10.05.1879
TELEGRAMM Osborn, Henry Fairfield Author: Osborn, Henry Fairfield Recipient: Haeckel, Ernst Dating: 16.02.1914
TELEGRAMM Britton, Nathaniel Author: Britton, Nathaniel Recipient: Haeckel, Ernst Corporation: Academy of Sciences New York Dating: 16.02.1894