DIN 19571-1
DIN 19571-1 Gully tops 500 × 500 for road gullies, class C 250, curve type - Part 1: Summary
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