1. Eric W. Weisstein, "Euler-Mascheroni Constant." From MathWorld—A Wolfram Web Resource. https://mathworld.wolfram.com/Euler-MascheroniConstant.html; D. Wells, The Penguin Dictionary of Curious and Interesting Numbers. Middlesex, England: Penguin Books, p. 28, 1986; J. Havil, Gamma: Exploring Euler's Constant. Princeton, NJ: Princeton University Press, 2003; J. H. Conway, and R. K. Guy, "The Euler-Mascheroni Number." In The Book of Numbers. New York: Springer-Verlag, pp. 260—261, 1996; R. P. Brent, "Computation of the Regular Continued Fraction for Euler's Constant." Math. Comput. 31, 771—777, 1977.
2. Martin Aigner, Günter M. Ziegler. Proofs from THE BOOK (4th ed.). Berlin, New York: Springer-Verlag. pp. 27—36 (1998). doi:10.1007/978-3-642-00856-6.
3. P. Solé, Y. Zhu. An Asymptotic Robin Inequality. Integers, A81, 16 (2016) http://math.colgate.edu/~integers/q81/q81.pdf; Y. Zhu, arXiv:1609.07555 [math.GM].
4. Dmitri Martila. (2023). A Simple Argument Proves the Riemann Hypothesis. Qeios. doi:10.32388/ZTG0NQ
5. Dmitri Martila. (2023). Nine one-page proofs of the Riemann Hypothesis. Qeios. doi:10.32388/5YFNXG. More is in my ORCID record, https://orcid.org/0000-0002-8087-823X