Central Pacific Railroad Photographic History Museum
Cprr Photographic History Museum: Builders of the Central Pacific Railroad
This chapter from "The First Transcontinental Railroad" by John Debo Galloway contains biographies of the important men who conceived of the railroad, found funds for the line, and engineered the construction.
Museum of the City of San Francisco
Virtual Museum of the City of San Francisco: Driving the Last Spike
Provides a short description of the development of the transcontinental railroad and the "Big Four" behind the construction. From the San Francisco News Letter of September 1925.