Application of building products in structures – Part 401: Rules for the application of clay masonry units according to DIN EN 771-1:2011-07
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 11/01/2012

Application of building products in structures – Part 401: Rules for the application of clay masonry units according to DIN EN 771-1:2015-11
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 01/01/2017