Rudolf von Ficker: Memorandum, Igls near Innsbruck, on 29. October 29, 1945; in the Schenk legacy of the Archive of the Society of the Friends of Music Vienna and in the Wellesz legacy of the music collection of the Austrian National Library; quoted in full by Gerhard Oberkofler: Orchideenfächer im Faschismus, in: Jahrbuch des Dokumentationsarchivs des österreichischen Widerstandes 1990, pp. 45-49, here pp. 47-49. See also Renate Erhart: Melanie Karoline Adler (1888-1942) (retrieved on 13 February 2012)
klahrgesellschaft.at
Yukiko Sakabe: The library of Guido Adler. In: Mitteilungen der Alfred Klahr Gesellschaft, volume 2007 No. 1 (March), pp. 10–13 available as pdf