There have been many books, reports, pamphlets, articles, etc. written about railroads in Indiana. Here, I have started a bibliography of them. More listings to come soon.

Historical and Current Railroads
Ghost Railroads of Indiana, Elmer Sulzer (Reprinted 1998).
Limiteds, Locals, and Expresses in Indiana, 1838-1971, Craig Sanders (2003).
Monon: The Hoosier Line, Gary and Stephen Dolzall (2nd ed, 2002).
Railroads of Indiana, Richard Simons and Francis Parker (1997).
The Indiana Rail Road Company: America's New Regional Railroad, Christopher Rund (2006).
The Pennsylvania Railroad at Bay, Richard Wallis (2001).
The Pennsylvania Railroad in Indiana, William Watt (2000).

Interurban
Indiana Railroad: The Magic Interurban, George Bradley (1991, reprinted 2003).
Moonlight in Duneland: The Illustrated Story of the Chicago South Shore and South Bend Railroad, Ronald Cohen, editor (1998).
South Shore: The Last Interurban : Revised Second Edition, William Middleton (1999).

Railroad-Related
40 Great Rail-Trails in Michigan, Illinois and Indiana (1994).
Indiana Railroad Depots: A Threatened Heritage, Francis Parker (1989).
Indianapolis Union Station: Trains, Travelers & Changing Times, James Hetherington (2000).