www.securerailconference.com/rail_education/sessiondetails.aspx?id=2489
www.bls.gov/oes/current/oes333052.htm
www.federalregister.gov/documents/2016/12/07/2016-29256/railroad-police-officers
www.therailroadpolice.com/
www.odmp.org/search/browse/railroad-police
www.trainorders.com/discussion/read.php?1,982334
https://sites.google.com/site/railroadpolicebadges/history
www.cowboysindians.com/2015/10/policing-the-rails/
www.signaturecoins.com/custom-railroad-police-coins
https://en.wikipedia.org/wiki/Railroad_police
https://en.wikipedia.org/wiki/Transit_police