I hope this isn't overkill, but I dug up a March 1973 issue of The Ballcard Collector, featuring this interview with legendary Topps official Bill Haber concerning 1973 Topps.
In other BCC issues, a collector reported that Ohio had all cards issued at once. Also, a Canadian columnist noted that the entire OPC set was released in late May, in a similar fashion to many parts of the US. Later in the year, the Card Collectors Company was advertising the Blue Checklist set (@$2.95), along with many test set items.
