When I was a kid, one of my favorite books was "Naissance d'une auto", about the development of the Renault 18 (yes, I was a weird kid). The car in itself is fairly bland but the book was very well made, as it covered every single step of the development of a new car, from the first meetings to the start of the production. It also included a big chapter about safety that was describing the state of the art at the time of the Renault 18's inception, so this is where I got to know the american ESVs from the seventies. Moreover, I recently read a post on an automotive blog about ESVs so that was fresh in my memory.
In this very case, what seems obscure to you is common to me, as I have been knowing the Fairchild ESV since I'm 7 or 8. But, believe me, even though I have collected hundreds of books and magazines in the last three decades, I am truly amazed to find on this site literally thousands of cars I have never, ever seen or even heard of. I feel really humble compared to the real pros here, whose knowledge of the most obscure contraption made in a derelict shed lost in the middle of nowhere is truly mind boggling.