Short series on BBC 4 over the last couple of weekends, Tones, Drones and Arpeggios. Looked at and interviewed La Monte Young, Terry Riley, Steve Reich and Glass. An interesting primer.
I had this too. If I recall it was a bonus issue if you purchased several albums from the series. There were tokens on the inner liner note. Hence the not for sale notice. My copy of .Leo Parker's"Let me tell you bout it" was also a similar bonus issue.
I have a couple of these boxes. I've no particular issues with the sound. Production is a bit shoddy with no personnels
Two reasons encouraged me to buy
They are an inexpensive way to fill the odd hole in my collection
They've enabled me to dispose of a few vinyl albums that are infrequently played and have no room for but I feel I can't do without the music.