Barry, Paul. “A New Group in the Riordan Family of Matrix Groups: The Sprugnoli Group”. The Electronic Journal of Combinatorics 33, no. 4 (November 6, 2026): #P4.29. Accessed November 6, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v33i4p29.