DIN 13971-2
DIN 13971-2 Dentistry - Orthodontic products - Part 2: Attachments for seating archwires in orthodontics
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 01/01/2000
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 01/01/2000