This site has material on a variety of railroad topics, both model railroads and real railroads. It also has materials about collecting model railroads.
This site began with “Guide to Z-Scale”, which was the next generation of material which originally appeared in Greenberg’s Guide to Märklin Z”(Greenberg Publishing, 1990; now out of print). When I gained the copyright to the text of that book, I updated the material and began the web site guidetozscale.com.
Things grew out from there with the addition of information about all sorts of things railroad.