This query will give the author fields and the note in a single query:

SELECT t1.*,t2.note_note FROM authors AS t1, notes AS t2
WHERE t2.note_id=t1.note_id AND t1.author_canonical='Robert A. Heinlein';

It should be noted ( :) ) that the notes field is somewhat depricated - it's not displayed in the ISFDB anymore as we rely more on Wikipedia for that data. So the notes that you find probably haven't been updated in a couple of years.