[1] M. Aigner, A course in enumeration, Graduate Texts in Mathematics, 238, Springer, Berlin, 2007.
[2] E. A. Bender, Asymptotic methods in enumeration, SIAM Rev., 16 (1974) 485–515.
[3] L. Comtet, Advanced combinatorics: the art of finite and infinite expansions, Dordrecht, Netherlands, Reidel, 1974.
[4] N. G. De Bruijn, Asymptotic methods in analysis, North-Holland Publishing Co., Amsterdam, 1961.
[5] P. Flajolet and R. Sedgewick, Analytic combinatorics, Cambridge University Press, 2009.
[6] I. S. Gradshteyn and I. M. Ryzhik, Table of Integrals, Series, and Products, 7th Edition, Academic Press, 2007.
[7] M. Hassani, Cycles in graphs and derangements, Math. Gaz., 88 (2004) 123–126.
[8] M. Hassani, Derangements and alternating sum of permutations by integration, J. Integer Sequences, 23 (2020) Article 20.7.8.
[9] M. Hassani, Enumeration by e, in T. M. Rassias and N. J. Daras, eds., Modern discrete mathematics and analysis: with applications in cryptography, information systems and modelling, Springer, 2018 227–233.
[10] M. Hassani, On a difference concerning the number e and summation identities of permutations, J. Inequal. Spec. Funct.,12 (2021) 14–22.
[11] L. Lovász, Combinatorial problems and exercises, 2nd ed., Amsterdam, Netherlands, North-Holland, 1993.
[12] A. M. Odlyzko, Asymptotic enumeration methods, in Handbook of combinatorics, 1, 2, Elsevier, Amsterdam, 1995 1063–1229.
[13] F. W. J. Olver, D. W. Lozier, R. F. Boisvert and C. W. Clark (editors), NIST Handbook of Mathematical Functions, Cambridge University Press, 2010.
[14] K. H. Rosen, J. G. Michaels, J. L. Gross, J. W. Grossman and D. R. Shier, Handbook of discrete and combinatorial mathematics, CRC Press, 2000.
[15] M. Z. Spivey, The art of proving binomial identities, CRC Press, 2019.
[16] E. C. Titchmarsh, The theory of functions, 2nd ed., Oxford University Press, 1975.
[17] E. W. Weisstein, CRC Concise encyclopedia of mathematics, 2nd ed., CRC Press, 2003.
[18] م. حسنی، ع. احمدی، جای خالی عدد نپر در کتابهای متوسّطه، ریاضی و جامعه، 1 (1393) 13--23.
)