The MP3 files that are no longer available for download from this site are now available
here.
I have no control over, nor responsibility for, the material on this Russian site and I can't help if any of the files are corrupted or incorrect in any way, so please don't send any emails to me if you discover a problem.
I'm grateful to Artyom for making the effort to keep these beautiful old recordings available, and I'm grateful to all the people who sent messages in support of this eccentric little experiment. Thanks to you all.