1. OIML R 75-1, 2002, Heat meters, Part 1: general requirements, International Organization of Legal Metrology.
2. OIML R 75-2, 2002, Heat meters, Part 2: type approval tests and initial verification tests, International Organization of Legal Metrology.
3. Measuring Instruments Directive (MID), http://www.ineprometering.com.
4. A technical consultation on the present status of heat meters in western Europe, PK & WISE Global Information, provided by Goulden Reports.
5. AGFW-Wärmezähler–Prüfprogramm IV, 2006, Abschlussbericht des 1. Durchganges.