Rails Sagebrush and Pine is a great introductory book with regard to the history of SVRy and the connecting logging lines. It is however a bit shallow in terms of a thorough study of SVRy history if compared to say the Colorado Rail Anuals, or any of Robert Turners books. No particular criticism intended toward the author as the book was written in the 1960's and I've seen a fair number of other rr books from that era that didn't dig too deep. I think it wasn't expected by the typical readership.
There is a modest paperback book on the SVRy that is sold at the SVRy depot gift shops. It has some unique photos and I think was in part put together by one of the descendents of the original owners of the rr. Sorry I don't have the name of the book. It can probably be ordered however from the SVRy depots during the operating season. If someone is interested I could find out the title and maybe the price.
There are some SVRy photos in another out of print book called "Stations West". Also, the Colorado Rail Anual that has a large article on the Utah Northern has a few SVRy photos. "Narrow Gauge Scenes" by Adolph Hungrywolf also has a bit about the SVRy and a few nice photos.