Back during the Cold War lots of artists published lots of pseudo pictures of pseudo airplanes. Some were American artists speculating about "undiscovered" Soviet aircraft, while others were deliberate attempts at distracting the opposition.
There were even a few inaccurate plastic scale models of "stealth" airplanes and the infamous "stealth" helicopter.
Bottom line, generals prefer public images to be months or years behind reality, just to keep the bad guys guessing.
What is the Russian word: maskarov?
I have a copy of that book which I inherited from my father along with a few other publications from the '80s. It had a lot of ultimately inaccurate art of the ATF, ATB, and the "F-19". If I recall correctly the author was then of the opinion that the "F-19" existed but had a different designation probably under the reconnaissance sequence.
None of the concepts resembled the real world F-117 which wasn't revealed until a few years later so I guess the disinformation worked pretty well.