German Aeroplane – The Grade. In: Flight, 2. Januar 1909, S. 3–4 (englisch); archive.org “It is reported from Berlin that an engineer named Grade had succeeded in making flights from 100 to 400 metres in length at an altitude of about 1 metre and at speeds varying from 30 to 40 kiloms. per hour.”
Herr Grade Has a Fall. In: Flight, 2. Oktober 1909, S. 612 (englisch); Textarchiv – Internet Archive „While making an attempt to win the Lanz Prize […]“
filmportal.de
Ziel in den Wolken. In: Filmportal.de, abgerufen am 20. Juni 2022. – 100 Min., 35 mm-Film, 1:1,37, s/w, Ton, Uraufführung: 1. Dezember 1938, Berlin.
