https://www.harnoncourt.org/en/the-archive/
“The Harnoncourt family has left Nikolaus Harnoncourt’s artistic legacy to the province of Upper Austria for digitisation – with the aim of securing it, making it accessible worldwide and processing it scientifically. The Nikipedia database fulfils this requirement and is constantly being expanded to include further works and content. So it’s always worth taking a look. Discover the universe of Nikolaus Harnoncourt!”
Via
https://theviolinchannel.com/nikolaus-harnoncourt-archive-launched-online/
Von Nikolaus Harnoncourt – http://images.derstandard.at/2016/03/06/brief.jpg, Gemeinfrei, Link