Mechanical Principles von Ralph Steiner

https://www.youtube.com/watch?v=Y5pen3QMgzQ Ralph Steiner Mechanical Principles 1930
https://www.youtube.com/watch?v=N4WA1gcIJio Ralph Steiner Mechanical Principles 1933 [Dauer: 10:34]

KEYWORDS: Mechanik, principle, Prinzip, Mechanische Prinzipien