I've collected a number of references related to this topic and will add them as I can. I started with the following cycles -- C01 (1946-51), C03 (1954-57), C04 (1957-60), C06 (1963-66), and C08 (1969-72). More to come...
18 May 2011
My request for further info in Zonal '?'s brought a number of helpful responses, some of them very detailed, which I'll tackle in a future post. One of the common threads across the responses was a summary of the qualification paths by players who qualified into the next stage, i.e. who qualified by what event into the interzonal (or knockout tournament). The best known overview of qualification paths is found on Glenn Giffen's zonal pages:-