According to this reference
, the first science fiction writer to posit an electronic book was Stanislaw Lem, in Return From the Stars
, in 1961. Just five years (and a fantastic paradigm shift) from your Heinlein book.
I love this...
I spent the afternoon in a bookstore. There were no books in it. None had been printed for nearly half a century. And how I have looked forward to them, after the micro films that made up the library of the Prometheus! No such luck. No longer was it possible to browse among shelves, to weigh volumes in hand, to feel their heft, the promise of ponderous reading. The bookstore resembled, instead, an electronic laboratory. The books were crystals with recorded contents. They can be read the aid of an opton, which was similar to a book but had only one page between the covers. At a touch, successive pages of the text appeared on it. But optons were little used, the sales-robot told me. The public preferred lectons - like lectons read out loud, they could be set to any voice, tempo, and modulation. Only scientific publications having a very limited distribution were still printed, on a plastic imitation paper. Thus all my purchases fitted into one pocket, though there must have been almost three hundred titles. My handful of crystal corn - my books. I selected a number of works on history and sociology, a few on statistics and demography, and what the girl from Adapt had recommended on psychology. A couple of the larger mathematical textbooks - larger, of course, in the sense of their content, not of their physical science. The robot that served me was itself an encyclopedia, in that - as it told me - it was linked directly, through electronic catalogs, to templates of every book on earth. As a rule, a bookstore had only single "copies" of books, and when someone needed a particular book, the contents of the work was recorded in a crystal.
The originals - Crystomatrices - were not to be seen; they were kept behind pale blue enamel the steel plates. So a book was printed, as it were, every time someone needed it. The question of printings, of their quantity, of their running out, had ceased to exist. Actually, a great achievement, and yet I regretted the passing of books.