Kellner, V. “Determination of the N-Nitrosodimethylamine Content of Beer and Malt (A Collaborative Trial): Submitted on Behalf of the Analysis Committee of the European Brewery Convention”. BrewingScience, vol. 52, no. 11/12, Dec. 1999, pp. 207-8, https://brewingscience.de/index.php/brewingscience/article/view/674.