Early Soviet era launch vehicles had a variety of designations, e.g. the well known Vostok launcher and its derivations have been known as the R7, 8K72, Semyorka, SS-6, Sapwood, A-1 and SL-3 .
I'm interested in the Western name sequence that is attributed as the "Sheldon name". I am assuming it was a U.S. civil designation as the SS-6 and Sapwood terms are NATO and SL-3 is US DoD. The RussianSpaceweb has a good list at http://www.russianspaceweb.com/rockets_launchers.html
I recall the Sheldon designation and others from childhood books about spaceflight. These had been compiled by western observers during the cold war from whatever inferences they could make. Paraphrasing from the link above the sequence was roughly:
A, A1, A2 Sputnik, Vostok, Soyuz, Molniya
B Kosmos 2
C Kosmos 1 and 3
Finally, the question:
What happened to designations E, H and I? I presume they might be a place holder for vehicles subsequently merged with other designations, but I'd be interested to hear the background to it.