Pittermann, W., and M. Kietzmann. “[Bovine Udder Skin (BUS): Testing of Skin Compatibility and Skin Protection] [Article in German]”. ALTEX - Alternatives to Animal Experimentation, vol. 23, no. 2, May 2006, pp. 65-71, https://www.altex.org/index.php/altex/article/view/842.