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
ESQ-1, SQ-80, TX81Z, D-50, D-550, VFX, VFXSD, SD-1,
Proteus/1, Proteus/2.

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

http://www.cesiumsound.com/