found: Kisters, Sebastian. "Ruhrpott, Ruhrpott", 2000:t.p. (Schalke 04)
found: Fussball Lexikon, c1991:p. 314 (Schalke 04, FC; est. 1904)
found: FC Schalke 04 website, Sept. 19, 2001
found: Wikipedia, May 22, 2020(FC Schalke 04; Fussballclub Gelsenkirchen-Schalke 04 e. V., commonly known as FC Schalke 04, Schalke, Schalke 04 or abbreviated as S04, is a professional German football and multi-sports club originally from the Schalke district of Gelsenkirchen, North Rhine-Westphalia; founded in 1904)