House, Robert (March 2006). "The Kozminski File". Ripperologist. New York City: Mango Books. Retrieved 21 March 2019 – via Casebook.org.
This is based on a statement by George R. Sims that a police suspect "had at one time been employed in a hospital in Poland" (in Lloyd's Weekly News, 22 September 1907; see copy at Casebook).
Curtis, L. Perry Jr. (April 2003). "Recent Scholarship on Jack the Ripper and the Victorian Media". Reviews in History: Covering books and digital resources across all fields of history. Institute of Historical Research, University of London. Archived from the original on 13 June 2011. Retrieved 7 September 2014.
"Akt urodzenia Aarona Mordki Kuźmińskiego" [Birth certificate of Aaron Mordke Kuźmiński]. Archiwum Państwowe w Poznaniu. 15 September 2014. Retrieved 15 September 2014.
Curtis, L. Perry Jr. (April 2003). "Recent Scholarship on Jack the Ripper and the Victorian Media". Reviews in History: Covering books and digital resources across all fields of history. Institute of Historical Research, University of London. Archived from the original on 13 June 2011. Retrieved 7 September 2014.