Kosswig, K. “Surfactants” in Ullmann’s Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. எஆசு:10.1002/14356007.a25_747.
Hans-Samuel Bien, Josef Stawitz, Klaus Wunderlich “Anthraquinone Dyes and Intermediates” Ullmann's Encyclopedia of Industrial Chemistry 2002 Wiley-VCH, Weinhem. எஆசு:10.1002/14356007.a02_355
Manfred Weber, Markus Weber, Michael Kleine-Boymann "Phenol" in Ullmann's Encyclopedia of Industrial Chemistry 2004, Wiley-VCH. எஆசு:10.1002/14356007.a19_299.pub2.