Hosh, Kafia (September 21, 2010). "Maryland answers SmarTrip with CharmCard". Washington Post. Baltimore, Maryland. p. B8. Archived from the original on November 17, 2010. Retrieved February 17, 2011.
Hosh, Kafia (September 21, 2010). "Maryland answers SmarTrip with CharmCard". Washington Post. Baltimore, Maryland. p. B8. Archived from the original on November 17, 2010. Retrieved February 17, 2011.