BRIEF [O.A.] Recklinghausen, Friedrich Daniel Author: Recklinghausen, Friedrich Daniel Recipient: Haeckel, Ernst Dating: 12.03.1868
BRIEF OHNE UMSCHLAG Schultze, Fritz Author: Schultze, Fritz Recipient: Haeckel, Ernst Dating: 24.03.1868
BRIEF [O.A.] Schultze, Leonhard Author: Schultze, Leonhard Recipient: Haeckel, Ernst Dating: 31.08.1868
BRIEF [O.A.] Schultze, Leonhard Author: Schultze, Leonhard Recipient: Haeckel, Ernst Dating: 22.02.1868
BRIEF OHNE UMSCHLAG Weismann, August Author: Weismann, August Recipient: Haeckel, Ernst Dating: 06.05.1868
BRIEF OHNE UMSCHLAG Pringsheim, Nathanael Author: Pringsheim, Nathanael Recipient: Haeckel, Ernst Dating: 10.08.1868
BRIEF OHNE UMSCHLAG Hein, Reinhold Author: Hein, Reinhold Recipient: Haeckel, Ernst Dating: 23.02.1868
