In his blog, Fred Pohl wrote about how Heinlein’s agent gave permission for Pohl publish the novel in If and to cut “five or ten thousand words in the beginning that were argumentative, extraneous and kind of boring” (and Pohl agreed to pay full rate for the cut words). But apparently, Heinlein “went ballistic” when he saw the first installment, so much so that when the book appeared as a separate publication, Heinlein made sure people knew who was responsible for the previous cuts by adding a note* that “A short version of this novel, as cut and revised by Frederik Pohl, appeared in Worlds of If Magazine.”
* The version of Heinlein’s note that Pohl recalled was much funnier
than Heinlein’s actual note in our timeline, but sadly, we have lost track of where we saw
Pohl’s version.