Turnabout TV-S 34610 (LP) Black Angels (Images I): thirteen images from the dark land for electric string quartet / George Crumb. String Quartet in Four Parts (1950) / John Cage

Side 1:
George Crumb: Black Angels (Images I): thirteen images from the dark land for electric string quartet (1970) 22:45

Side 2:
John Cage: String Quartet in Four Parts (1950) 21:44

The Concord String Quartet: Mark Sokol and Andrew Jennings, violin. John Kochanowski, viola. Norman Fischer, cello

Recorded (analog) in 1972
Originally released as part of the 3-LP box Vox SVBX-5306 (1973).
These recordings are currently available (with several other works) on CD: VoxBox CDX 5143
This LP released in 1976

Sources: New Albion Discography, Cornell University Library Catalog and VoxBox CDX 5143, Paul van Emmerik: Diskographie in "John Cage - Musik-Konzepte Sonderband II"