Good luck with that!
I expect you'll find they're hard to come by these days - especially since ECRI prefer that you buy them (and they're not cheap).
Meanwhile - in case other folk don't know what they are like - here's
As mentioned before, they were OK in the past (when not much else was available), but they're probably a bit dated now. I would be happy to be proved wrong, but I sense that ECRI has not continued to develop the series much over the years.
But if you get any joy, be sure to update this
If I were you, I would develop your own ... and maybe think about using Fluke Ansur.