This booklet from the Society of American Magicians from 1957 has some interesting stuff inside it.
One of the interesting things was their rules for magic books:
Section C above means all those Ed Harris Jumbo Dollars that teach magic tricks on the back are violations of this section. It also makes giving away any promo that teaches a trick a violation. I don’t know if this is still in their current by-laws, but it highlights how tightly held magic secrets were at one point, compared to now.
-Louie