Pennsylvania Railroad class S1 (English Wikipedia)

"It's a bird! It's a plane! No, it's - an office tool". The Home Forum > Essays. The Christian Science Monitor. September 23, 2004. Retrieved 2007-09-04.

espacenet.com

"US2128490A Locomotive". Espacenet. 3 August 1938. Archived from the original on 11 March 2024. Retrieved 11 March 2024.

"PRR S-1 Duplex (Volume 1)". YouTube. 25 May 2018. Archived from the original on 2021-12-05.

"Actual Production Models Shown". Brochures. www.lionel.com. 2003. Retrieved 2007-09-03.

"PRR Chronology 1936" (PDF). PRR Chronology. Pennsylvania Technical and Historical Society. April 2015. Retrieved 2018-07-21.
"PRR Chronology 1937" (PDF). PRR Chronology. Pennsylvania Technical and Historical Society. April 2015. Retrieved 2018-07-21.
"PRR Chronology 1937" (PDF). PRR Chronology. Pennsylvania Technical and Historical Society. April 2015. Retrieved 2018-07-21.
"PRR Chronology 1945" (PDF). PRR Chronology. Pennsylvania Technical and Historical Society. April 2015. Retrieved 2016-02-20.
A GENERAL CHRONOLOGY OF THE PENNSYLVANIA RAILROAD COMPANY 1939 | http://www.prrths.com/newprr_files/Hagley/PRR1939%204_15_15.pdf

"Raymond Loewy-Locomotives". The Avanti. Archived from the original on 2007-09-27. Retrieved 2007-09-02.

Pennsy's “Big Engine” in the snow | Classic Trains Magazine | April 1st, 2014 | https://ctr.trains.com/photo-of-the-day/2014/04/pennsys-big-engine-in-the-snow Archived 2020-09-21 at the Wayback Machine

"Raymond Loewy-Locomotives". The Avanti. Archived from the original on 2007-09-27. Retrieved 2007-09-02.
"US2128490A Locomotive". Espacenet. 3 August 1938. Archived from the original on 11 March 2024. Retrieved 11 March 2024.
Waide Collection of Vintage Railroad Advertisements 1840-1949 https://waidephoto.smugmug.com/Trains/Waide-Collection-of-Vintage/i-NcMc82c/A Archived 2021-10-28 at the Wayback Machine
Pennsy's “Big Engine” in the snow | Classic Trains Magazine | April 1st, 2014 | https://ctr.trains.com/photo-of-the-day/2014/04/pennsys-big-engine-in-the-snow Archived 2020-09-21 at the Wayback Machine
https://prrt1steamlocomotivetrust.org/faq.php Archived 2019-08-24 at the Wayback Machine | Question No.9 "Where it will run?"

"PRR S-1 Duplex (Volume 1)". YouTube. 25 May 2018. Archived from the original on 2021-12-05.