William was born in 1814. He passed away in 1884.
"United States Census, 1860", database with images, FamilySearch (https://www.familysearch.org/ark:/61903/1:1:M69H-W1X : 11 November 2020), Wm O Sellman, 1860.
"United States Census, 1870", database with images, FamilySearch (https://www.familysearch.org/ark:/61903/1:1:MN3J-RWM : 2 January 2021), Wm O Sellman, 1870.
"United States Census, 1880," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MNQR-S71 : 15 August 2017), William Sellman, Medleys, Montgomery, Maryland, United States; citing enumeration district ED 110, sheet 266A
https://www.findagrave.com/memorial/6746299/william-oliver-sellman