Salasoo, Lembit & Topinka, Jennifor. 21st Century Locomotive Technology: Quarterly Technical Status Report 17 DOE/AL68284-TSR17, report, May 21, 2007; (https://digital.library.unt.edu/ark:/67531/metadc882190/m1/1/: accessed October 16, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .