Book, book, book. and that ain't chicken-scratch, no matter how you look at it.
From
www.asimovonline.com/asimov_FAQ.html#starters1"Just how many books did Asimov write?
Short answer: An awful lot. Hundreds.
Long answer: Well, it depends on how you count them.
For example, the most complete Asimov bibliography which Asimov himself had a hand in preparing is the catalogue in I. Asimov: A Memoir. It lists 469 items, including 2 wall posters and a calendar (which some people might not be inclined to count as "books".) It also lists 117 science fiction anthologies, none of which are entirely by Asimov, and many of which include no stories by him (and so some people might be inclined not to count those.) There are also books which were almost entirely written by someone else (the Superquiz books, From Harding to Hiroshima, the Book of Facts) which Asimov counted because he had an extensive role in the editing of the book. Some books were counted more than once if Asimov did extensive work on later editions (such as the Biographical Encyclopedia.) And, of course, Asimov recycled many of his stories and essays so that they appeared in more than one collection, and some books are nothing but recyclings of older books..."