http://newgon77idcem62vqlfge3jkidjenvf6afhxwr2napk4kpp2labjbdid.onion/wiki/Guy_Strait
It seems clear however that if Guy Strait, the man with a "corner on the market" was averaging less than $300,000 a year total from many kinds of pornography, of which child porn was only a part, it's just not possible that child pornography was a multi-million dollar business in the 1970's.