^Cite error: The named reference Cochrane1895 was invoked but never defined (see the help page).
^Cite error: The named reference BostonDailyAdvertiser1896 was invoked but never defined (see the help page).
^"S. H. Roper, of Roxbury [...]", Lowell Daily Citizen and News, no. 2050, Lowell, Massachusetts, 6 January 1863, S. H. Roper, of Roxbury, has invented a steam wagon for common roads, which stops, turns corners, backs, 'keeps to the right as the law directs,' and does many other intelligent things under the hands of a skilful driver.
^"Miscellaneous Items; Mr Sylvester H Roper of Roxbury, Mass has invented a steam carriage…", New Haven Daily Palladium, no. 52, New Haven, Connecticut, 3 March 1863
^Falco, Charles M.; Guggenheim Museum Staff (1998), "Issues in the Evolution of the Motorcycle", in Krens, Thomas; Drutt, Matthew (eds.), The Art of the Motorcycle, Harry N. Abrams, pp. 24–31, 98–101, ISBN0-89207-207-5 Michaux-Perreaux year 1868. Roper year 1869.{{citation}}: CS1 maint: postscript (link)