Government map of Nicaragua : from the latest surveys ordered by President Patricio Rivas and Genl. William Walker ;executed under the supervision of the Señor Fermín Ferrer;Governor of the Western Department;1856. Jocelyn;Albert H. New York. Library of Congress Geography and Map Division. G4850 1856 .G6. http://hdl.loc.gov/loc.gmd/g4850.ma001010AccessedJuly252023.