William Brennan - line 25
Source - Year: 1870; Census Place: Barclay, Black Hawk, Iowa; Roll: M593_377; Page: 306A; Image: 21; Family History Library Film: 545876.
William Brennan - line 40
Source - Year: 1880; Census Place: Barclay, Black Hawk, Iowa; Roll: 327; Family History Film: 1254327; Page: 363C; Enumeration District: 041; Image: 0348.
William Brennan - line 42
Source - Year: 1900; Census Place: Waterloo, Black Hawk, Iowa; Roll: T623_418; Page: 20A; Enumeration District: 22.
William Brennan - line 20
Source - Year: 1910; Census Place: Waterloo Ward 4, Black Hawk, Iowa; Roll: T624_392; Page: 16A; Enumeration District: 0026; Image: 911; FHL Number: 1374405.
Source - Year: 1915; Iowa State Census Collection, 1836-1925; Census Place: Waterloo, Black Hawk, Iowa; Roll: IA1915_35; Image: 3405