A couple of places to look:
Gives the history according to Bronica.
Also BUG, Bronica Users Group, in Yahoo groups.
Jonathan Taylor, moderator, posted a complete list of every ETR lens ever made, with specs, etc.
Includes the early silver nose ones. And the delectable Super Angulon Tilt-Shift.
Click "Files" on the upper left of the main page, then scroll down slightly and you will see the list title.
EDIT: Adding link to Jos. Schneider archive about the 55mm Tilt-Shift: