DIN 69893-5
DIN 69893-5 Hollow taper shanks with flat contact surface - Part 5: Hollow taper shanks type E; Dimensions and design
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 10/01/2012
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 10/01/2012