2012DIN 4844-1:2012-06 Graphical symbols - Safety colours and safety signs - Part 1: Observation distances and colorimetric and photometric requirements
2012DIN 4844-1:2012 Graphical symbols - Safety colours and safety signs - Part 1: Observation distances and colorimetric and photometric requirements
2005DIN 4844-1:2005 Graphical symbols - Safety colours and safety signs - Part 1: Design principles for safety signs in workplaces and public areas (ISO 3864-1:2002 modified)