Chobanov, G., and I. Chobanov. “Newtonian and Eulerian Dynamical Axioms. VI. Inductio Per Enumerationem Simplicem”. Ann. Sofia Univ. Fac. Math. And Inf., vol. 86, no. 2, Dec. 1994, pp. 99-122, https://stipendii.uni-sofia.bg/index.php/fmi/article/view/508.