Walter PTAK may have been the s/o Stanley and Stella. In the 1930 census (taken April 12th) they lived in Wyandotte, Wayne, MI: head, Stanley, 45, first md at 22, Poland Pol Pol, immigrated 1890, naturalized, laborer-alkali plant wife, Stella, 43, first md at 17, Poland Pol Pol, immigrated 1910, naturalized son, Walter, 19, MI son, Edward, 15, MI son, Arthur, 13, MI dau, Irene, 10, MI son, Ralph, 5, MI son, Raymond, 3-10/12, MI
The only deaths I am reasonably sure match those above are Edward and Arthur.
Edward, b 25 Feb 1915, d 29 Nov 1993, possibly in Duluth, MN. Arthur, b 11 May 1917, d 7 May 1991, in Hamilton Co. OH. If you want to continue the search you could request Edward's obit from the Duluth Public Library and then search for his survivors. There is an Obituary Request form at http://dlibrary.cpinternet.com/scripts/runisa.dll?dlibrary:pgobitsearch/http://dlibrary.cpinternet.com/scripts/runisa.dll?dlibrary:pgobitsearch/.