1910 United States Federal Census, Database online. Year: 1910; Census Place: St Paul Ward 7, Ramsey, Minnesota; Roll: T624_720; Page: 12B; Enumeration District: 104; Image: 456.Record for Peter Otto
1920 United States Federal Census, Database online. Year: 1920; Census Place: St Paul Ward 7, Ramsey, Minnesota; Roll: T625_854; Page: 16A; Enumeration District: 82; Image: 265.Record for Peter Otto
1880 United States Federal Census, Database online. Year: 1880; Census Place: Saint Paul, Ramsey, Minnesota; Roll: T9_631; Family History Film: 1254631; Page: 440.4000; Enumeration District: 222; Image: 0295.Record for Peter Otto