For those working with ex-Soviet equipment from the 60’s and 70’s here’s a remarkable resource: https://www.govinfo.gov/content/pkg/GOVPUB-C13-6925b02fb6dcaa88935be001eb551b4c/pdf/GOVPUB-C13-6925b02fb6dcaa88935be001eb551b4c.pdf
I am astonished that I found it in this in the US National Bureau of Standards (today NIST) archives 😊 Tim N3QE
