"New York, New York City Births, 1846-1909," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:2W46-CLH : 11 February 2018), Joseph Marcus, 20 Jan 1899; citing Manhattan, New York, New York, United States, reference cn 2155 New York Municipal Archives, New York; FHL microfilm 1,984,424.
* "New York State Census, 1905," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:SPX7-4W5 : 20 July 2018), Abram Marcus, Manhattan, A.D. 08, E.D. 04, New York, New York; citing p. 60, line 18, various county clerk offices, New York; FHL microfilm 1,432,883.
"United States Census, 1910," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M54Z-VWC : accessed 19 July 2019), Benjamin Rotbel, Brooklyn Ward 26, Kings, New York, United States; citing enumeration district (ED) ED 796, sheet 16B, family 293, NARA microfilm publication T624 (Washington D.C.: National Archives and Records Administration, 1982), roll 978; FHL microfilm 1,374,991.
"United States Census, 1930," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:X76Y-3ZB : accessed 19 July 2019), Abraham Marcus, Brooklyn (Districts 1001-1250), Kings, New York, United States; citing enumeration district (ED) ED 1202, sheet 18A, line 5, family 357, NARA microfilm publication T626 (Washington D.C.: National Archives and Records Administration, 2002), roll 1492; FHL microfilm 2,341,227.