Motocross MX1 is publishing a short series of articles on the History of World Motocross Championship. Part 1 of the series is up now. Parts 2-4 will be published in the next few weeks.
If they are as poor as Part 1 there isn’t much point in reading them. Not much history here — there are about 5 2-sentence paragraphs to cover the period from 1957-1972. Bummer.