Mininni, Michele; Orlando, Giuseppe; Taglialatela, Giovanni (2021-06-01). "Challenges in approximating the Black and Scholes call formula with hyperbolic tangents". Decisions in Economics and Finance. 44 (1): 73–100. arXiv:1810.04623. doi:10.1007/s10203-020-00305-8. ISSN1129-6569. S2CID224879802.
Mininni, Michele; Orlando, Giuseppe; Taglialatela, Giovanni (2021-06-01). "Challenges in approximating the Black and Scholes call formula with hyperbolic tangents". Decisions in Economics and Finance. 44 (1): 73–100. arXiv:1810.04623. doi:10.1007/s10203-020-00305-8. ISSN1129-6569. S2CID224879802.
Jaeckel, P. (March 2017). "Implied Normal Volatility". Wilmott Magazine: 52–54. Note The print version contains typesetting errors in the formulae which have been correct on www.jaeckel.org.
Mininni, Michele; Orlando, Giuseppe; Taglialatela, Giovanni (2021-06-01). "Challenges in approximating the Black and Scholes call formula with hyperbolic tangents". Decisions in Economics and Finance. 44 (1): 73–100. arXiv:1810.04623. doi:10.1007/s10203-020-00305-8. ISSN1129-6569. S2CID224879802.
Mininni, Michele; Orlando, Giuseppe; Taglialatela, Giovanni (2021-06-01). "Challenges in approximating the Black and Scholes call formula with hyperbolic tangents". Decisions in Economics and Finance. 44 (1): 73–100. arXiv:1810.04623. doi:10.1007/s10203-020-00305-8. ISSN1129-6569. S2CID224879802.