Sources

Stradling, David, and Joel A. Tarr, “Environmental Activism, Locomotive Smoke, and the Corporate Response: The Case of the Pennsylvania Railroad and Chicago Smoke Control,” The Business History Review 73, no. 4 (1999): 679, https://doi.org/10.2307/3116130.

Stradling, David, and Peter Thorsheim, “The Smoke of Great Cities: British and American Efforts to Control Air Pollution, 1860-1914,” Environmental History 4, no. 1 (1999): 8, https://doi.org/10.2307/3985326.

Szymanski, Ann-Marie, “Regulatory Transformations in a Changing City: The Anti-Smoke Movement in Baltimore, 1895–1931," The Journal of the Gilded Age and Progressive Era 13, no. 3 (July 2014): 351, https://doi.org/10.1017/S153778141400022X.

Ponnet vs. Souther Railway Company, (Fairfax Cir. 1915).

Union Station, Washington, D.C. -- Proposed Application of Smoke Law to Locomotives. Committee on the District of Columbia. Senate. Washington: Government Printing Office, 1907. From ProQuest, 2008. https://congressional.proquest.com/congressional/result/pqpresultpage.gispdfhitspanel.pdflink/$2fapp-bin$2fgis-hearing$2fe$2f3$2fc$2f5$2fhrg-1907-dcs-0002_from_1_to_57.pdf/entitlementkeys=1234%7Capp-gis%7Chearing%7Chrg-1907-dcs-0002