
patent z 1918 (Harry James Watts):
http://books.google.com/patents?id=mPJc ... q=&f=false
watek z ktorego ruscy wzieli zdjecia:
http://bbs.homeshopmachinist.net/showth ... =92&page=4
wiecej:
http://upper.us.edu/faculty/smith/reuleaux.htm
i jeszcze wiecej:
http://web.mat.bham.ac.uk/C.J.Sangwin/h ... tions.html