Mentioned on the TUHS mailing list https://www.tuhs.org/pipermail/tuhs/2024-September/030872.html
Some interesting documents are
There Is No Royal Road to Programs - A Trilogy on Raster Ellipses and Programming Methodology (M. Douglas McIlroy)
MM 67-4734-7 1967-05-15 2.54 MB An Introduction to the Available Programs and Other Design Aids for the Design of Filters, Equalizers and Other Networks
MM 67-5311-18 1967-08-29 1.27 MB Notes on the Design of Cosine Roll-Off Filters

A few days later, Chet Ramey posted https://www.tuhs.org/pipermail/tuhs/2024-October/030946.html the link https://www.telecomarchive.com/bstj.html where the Bell System Technical Journal from 1922 to 1996