R. B. Gardner and M. Gladin, “A Type of Eneström-Kakeya Theorem for Quaternionic Polynomials Involving Monotonicity with a Reversal”, Armen.J.Math., vol. 17, no. 4, pp. 1–10, May 2025, doi: 10.52737/18291163-2025.17.4-1-10.