Reich, Mike. “A Short Biography of Hubert Ludwig and a Note on the Publication Dates of His Monograph Die Seewalzen (1889–1892)”. Zootaxa 4052, no. 3 (December 3, 2015): 332–344. Accessed April 4, 2025. https://mapress.com/zt/article/view/zootaxa.4052.3.3.