Patil, D. P., and G. Tamone. “On Type Sequences and Arf Rings”. Annales Universitatis Paedagogicae Cracoviensis Studia Mathematica 6 (February 28, 2007): 35–50. Accessed October 31, 2026. https://studmath.uken.krakow.pl/article/view/13278.