Gardner, Robert B., and Matthew Gladin. “A Type of Eneström-Kakeya Theorem for Quaternionic Polynomials Involving Monotonicity With a Reversal”. Armenian Journal of Mathematics 17, no. 4 (May 15, 2025): 1–10. Accessed May 9, 2026. http://test.armjmath.sci.am/index.php/ajm/article/view/1262.