Cita APA (7th ed.)

Schaxel, J. (1987). Julius Schaxel an Ernst Haeckel. Urania-Verlag.

Cita Chicago (17th ed.)

Schaxel, Julius. Julius Schaxel an Ernst Haeckel. Leipzig: Urania-Verlag, 1987.

Cita MLA (8th ed.)

Schaxel, Julius. Julius Schaxel an Ernst Haeckel. Urania-Verlag, 1987.