CO2 motors have received a small share of publicity in the modelling press in their time. There have been a few articles, either as presentations of new motors or even tests and analysis of their performance.
Here is what I have found so far.
Starting of with November 1985 Aeromodeller and my favorite article, the presentation of the Brown A-23 by Mike Billington
Going back to April 1977 Aeromodeller, presentation of the Powermax Shark motor. Not the best of scans, I am afraid, do not remember where I found it.
Again Aeromodeller, this time February 1985, Telco motor analysis by Mike Billington
The Gasparins get their fair share of exposure in Aeromodeller, probably sometime in 1992, by Klaus Joerg Hammerschmidt
The last Brown motors to be designed and produced, the GB-12 single and GB-24 twin, presented by Klaus Joerg Hammerschmidt in Aeromodeller, sometime in 1994 I think
The Gasparin GM-300, again by K.J.H., in Aeromodeller
And the Mistral, again in Aeromodeller.
I have all these issues, however the scans did not come from them, else I would have noted the dates. Too lazy to search for them now, I guess.
Again the Brown A-23, this time from June 1981 Model Builder, a short presentation by Bill Hannan.
The Swiss Heibi motor, in Septmember 1992 Model Builder.
The Brown GB-12 and GB-24 presented in Bill Hannan's column, "Hannan's Hangar", Model Builder, September 1994.
And in the same issue, a presntation of the Russian DP-03, by Skip Ruff. Together with the foam RTF plane it used to be sold.
Two extremes in the same issue...