Safety rules for the construction and installation of lifts – Basics and interpretations – Part 11: Interpretations related to EN 81 family of standards; German version CEN/TS 81-11:2009
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 11/01/2009

Safety rules for the construction and installation of lifts – Basics and interpretations – Part 11: Interpretations related to EN 81 family of standards; German version CEN/TC 81-11:2011
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 06/01/2011