Körmendi, K. Contemporary piano music [SR] p1984 program notes (Karlkheĭnt︠s︡ Shtokkhauzen [in cyrillic])
MLA-L (Karlheinz Stockhausen; d. Dec. 5, 2007)
nytimes.com on www, Dec. 7, 2007 (Karlheinz Stockhausen; d. Dec. 5, 2007; age 79; German composer)
German Wikipedia WWW site, Dec. 7, 2007 (Karlheinz Stockhausen; b. Aug. 22, 1928, Mödrath, now Kerpen; d. Dec. 5, 2007, Kürten-Kettenberg; German composer, regarded as one of the most significant composers of the 20th century)