I only learned of Three Worlds as being a distributor of the Lectron System in October of 2016 through an eBay auction.
The company was located in Hampshire, IL. I have been researching the history of this company with little success. More information will be added as research results are obtained.
Three Worlds was very much like Creative Playthings of Princeton, NJ in that the company specialized in selling a variety of educational toys for children.
The sold model was a Raytheon Series 3 A packaged in a rebranded Series 3 A box.
I acquired two units of this model on eBay. Unfortunately, neither unit had any documentation at all so I do not have a release date. I would have loved to see how the manual was branded!