There doesn't seem to be a single Bronica information site (like the wonderful "K Mount Site" for Pentax), Tamron still have manuals online but that doesn't help much if (for example) you're trying to figure out when details were changed or indeed whether they were changed for the entire lifespan. For example, a lot of ETR accessories appear to have been marked "ETR" even when the camera body had changed to the ETRS or ETRSi so you've no idea how old something is. Not that it makes a lot of difference (as all backs, viewfinders, speed grips and lenses will fit all bodies) but it'd still be interesting to collectors.