just to say theres a lengthy interview with the author in this months uk Infinity magazine (
https://infinitymagazine.co.uk/product/infinity-issue-28-star-trek-the-motion-picture/ ). flicked through and read abit in the supermarket on my weekly grocery shop (will probably buy it next time).. and he goes into detail of the research and writing of the lost Cinefantastique double issue and later its resurrection as the Creature Feature book. (one particular funny anecdote is about his final interview with Shatner at Shatners favourite restaurant, they finish the meal and thinking of desert so shatner asks him 'do you like chocolate?' the author says yes and shatner tells the waiter 'you know to bring him'...and then comes out shatners favourite desert the most decadent melted chocolate cake the guy had ever seen which he tucked into as shatner watched finally allowing himself one spoonful as he was still on his strict diet for TMP even though filming had finished as he still had all the press publicity tours to do and didnt want to put any weight on for the journalists to go on the attack lol)