If you were around in the late 1980s and early 1990s you may
remember Cesium Sound full page ads in Keyboard and Electronic
Musician, or you may have gotten a famous "blue flyer".

Sound libraries are still available on Sysex disks for
01/W, SY-85, JD-990, ESQ-1, SQ-80, TX81Z, D-50, D-550, VFX,
VFXSD, SD-1, Proteus/1, Proteus/2, and Wavestation.

Also sounds for Wavestation, 01/W, SY-85 and JD-990.

http://www.cesiumsound.com/