Portable electrical apparatus for the measurement of combustion flue gas parameters – Guide to their use in the process of commissioning, servicing and maintaining gas fired appliances; German version CLC/TS 50612:2016
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 02/01/2017

Portable electrical apparatus for the measurement of combustion flue gas parameters – Guide to their use in the process of commissioning, servicing and maintaining gas fired central heating boilers; German version CLC/TS 50612:2013
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 11/01/2014