O'Keefe, John A.; Roman, Nancy G.; Yaplee, Benjamin S.; Eckels, Ann (2013). Ellipsoid Parameters from Satellite Data. pp. 45-51. doi:10.1029/GM004p0045. ISSN23288779.
United States Census, 1940, database with images, FamilySearch : accessed 8 July 2019, Maryland > Baltimore City > Baltimore City, Baltimore City, Ward 28 > 4-887 Baltimore City Ward 28 (Tract 28-4 - part) > image 5 of 36; citing Sixteenth Census of the United States, 1940, NARA digital publication T627. Records of the Bureau of the Census, 1790 - 2007, RG 29. Washington, D.C.: National Archives and Records Administration, 2012.
O'Keefe, John A.; Roman, Nancy G.; Yaplee, Benjamin S.; Eckels, Ann (2013). Ellipsoid Parameters from Satellite Data. pp. 45-51. doi:10.1029/GM004p0045. ISSN23288779.