"Illinois, Cook County, Birth Certificates, 1871-1940," database, FamilySearch (https://familysearch.org/pal:/MM9.1.1/QKDZ-4K6G : 18 May 2016), Henry Polk Or Pokovitz in entry for Sol Polovitz Or Polk, 14 May 1917; citing Chicago, Cook, Illinois, United States, reference/certificate 203922, Cook County Courthouse, Chicago; FHL microfilm .
"United States Social Security Death Index," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:J181-L48 : 20 May 2014), Sol Polk, 15 May 1988; citing U.S. Social Security Administration, Death Master File, database (Alexandria, Virginia: National Technical Information Service, ongoing).
