Mead, D. G., « The Equation of Ramanujan-Nagell and [y2] », Proceedings of the American Mathematical Society, vol. 41, no 2, , p. 333–341 (DOI10.2307/2039090, JSTOR2039090, lire en ligne).
Gillman, Leonard, « Review: Polynomials, Power Series, and Calculus by Howard Levi », The American Mathematical Monthly, vol. 81, no 5, , p. 532–533 (DOI10.2307/2318616, JSTOR2318616).
Mead, D. G., « The Equation of Ramanujan-Nagell and [y2] », Proceedings of the American Mathematical Society, vol. 41, no 2, , p. 333–341 (DOI10.2307/2039090, JSTOR2039090, lire en ligne).
Bezuszka, S. J., « Review: Foundations of Geometry and Trigonometry by Howard Levi », The American Mathematical Monthly, vol. 72, no 5, , p. 565 (DOI10.2307/2314158, JSTOR2314158)
Chakerian, G. D., « Review: Topics in Geometry by Howard Levi », The American Mathematical Monthly, vol. 76, no 8, , p. 962 (DOI10.2307/2317992, JSTOR2317992)
Gillman, Leonard, « Review: Polynomials, Power Series, and Calculus by Howard Levi », The American Mathematical Monthly, vol. 81, no 5, , p. 532–533 (DOI10.2307/2318616, JSTOR2318616).
Mead, D. G., « The Equation of Ramanujan-Nagell and [y2] », Proceedings of the American Mathematical Society, vol. 41, no 2, , p. 333–341 (DOI10.2307/2039090, JSTOR2039090, lire en ligne).
Lott, Fred W., « Review: Elements of algebra by Howard Levi », The Mathematics Teacher, vol. 48, no 5, , p. 353–354 (JSTOR27954922)
Lee, Herbert L., « Review: Elements of algebra by Howard Levi », The Scientific Monthly, vol. 80, no 6, , p. 387 (JSTOR21575)
Rajaratnam, Nageswari, « Review: Elements of algebra by Howard Levi », The Mathematics Teacher, vol. 53, no 7, , p. 585–586 (JSTOR27956256)
Bezuszka, S. J., « Review: Foundations of Geometry and Trigonometry by Howard Levi », The American Mathematical Monthly, vol. 72, no 5, , p. 565 (DOI10.2307/2314158, JSTOR2314158)
Chakerian, G. D., « Review: Topics in Geometry by Howard Levi », The American Mathematical Monthly, vol. 76, no 8, , p. 962 (DOI10.2307/2317992, JSTOR2317992)