​Discrete Signals and Inverse Problems – An Introduction for Engineers and Scientists by J.Carlos Santamarina and Dante Fratta has been made publicly available through EGEL. Dante Fratta is an associate professor of civil and environmental engineering at the University of Wisconsin, Madison, and has worked with ANPERC's Carlos Santamarina to write and update this textbook since it was originally published in 1998. Its latest edition is now available for free download here.