There are slides devoted to this topic: Lecture 8, pp. 23-29.
The Computer History Museum and the Columbia History of Computing sites both have information on core memory–with the CHM focusing on the patent disputes over its invention, and Columbia on its later evolution.
The University of Sydney’s page on core memory, on the other hand, focuses on the way the system worked.
This detailed page on “Magnetic Core Memory Systems” delves into both the history and usage of core memory, using circuit diagrams and technical language to explain the concept to computer hardware specialists.
Try out this interactive tutorial on magnetic core memory, which shows how the individual cores were written and read.
Read selections from From the Ranch to System Dynamics: An Autobiography by Jay Forrester.