McCullough, David. The Johnstown Flood. New York: Simon and Schuster, 1968.

A well-researched and well-written account of the great Johnstown Flood of 1889.

McCullough, Hax and Mary Brignano. The Search for Safety: A History of Railroad Signals and the People Who Made Them. Pittsburgh: Union Switch and Signal Division, American Standard Inc., 1981.

Company-sponsored history of signaling.

McGough, Michael R. The 1889 Flood in Johnstown, Pennsylvania. Gettysburg, PA: Thomas Publications, 2002.

A book filled with period photographs, drawings of the dam, a detailed history using interviews and testimony of people associated with the event.

Homepage of the National Park Service, Johnstown Flood Museum http://www.nps.gov/jofl/

Johnstown Flood Museum http://www.jaha.org/

A site with links to the Johnstown Flood Museum and other attractions in Johnstown to tell the story of the flood from the perspective of the residents of the communities.

Operation Lifesaver for Kids http://www.oli.org/for_kids/index.html

Operation Lifesaver is a national, non-profit agency devoted to eliminating collisions, injuries, and fatalities related to railroads. This section of their website gives activities, coloring pages, an art gallery of student posters, career opportunities, and an interactive called Safetyville.

Railroad Museum of Pennsylvania, http://www.rrmuseumpa.org/index.shtml

Great site for a comprehensive history of railways in Pennsylvania