Molly and Tenbrooks - Bill Monroe and his Blue Grass Boys (December 6, 1947) (cut-off partial)

Bill Monroe and His Blue Grass Boys (1950- 60) Vol. 2 [1974] - Bill Monroe & His Blue Grass Boys

Bill Monroe - Swing Low Sweet Chariot (1944)

Hank Williams - My Heart Would Know - 1951 Hillbilly - MGM K11000

Marvin Rainwater - Moanin' The Blues - 1958 Rock N Roll - MGM K12665

Hank Williams - Cold Cold Heart (STEREO mixed live classic country performance from 1952 )

Which lineup of musicians established the definitive bluegrass sound known today? Bill Monroe, Earl