Biendl, M., and S. B. Sørensen. “Determination of Iso-Alpha-Acids and Reduced Iso-Alpha-Acids (Rho, Tetra, Hexa) in Hop Products by HPLC Using a Modified Version of Analytica-EBC Method 7.8: Submitted on Behalf of the EBC Analysis Committee”. BrewingScience, vol. 57, no. 7/8, Aug. 2004, pp. 44-45, https://brewingscience.de/index.php/brewingscience/article/view/553.