Heinlein and "Dr.Renshaw"

10 years later… His second wife was the source of one his pseudonyms, Anson MacDonald, which he used when he had more than one story in an issue of Astounding and for some non-future history stories.

As for Asimov’s memory, though I don’t remember exactly I believe he talked about it during the 1970 MITSFS picnic he went to (his last time.) He demonstrated it by singing all the verses of the Star Spangled banners, which he said came in handy when some right winger accused him of being a Communist.

And thus clearly proving that he was actually a German spy, because no real American would actually know (or even know of the existence of) any verse beyond the first.