Complex sentence: Basie credits Billy Eckstine, a top male vocalist of the time, for prompting his return to Big Band and Norman Granz for getting him into the Birdland club and promoting the new band through recordings on the Mercury, Clef, and Verve labels.
Split into simpler sentences: Basie credits Billy Eckstine, a top male vocalist of the time, for prompting his return to Big Band. He said that Norman Granz got them into the Birdland club and promoted the new band through recordings on the Mercury, Clef, and Verve labels.