One reason I'm the mental leviathan I am today is because my parents were suckers for encyclopedia salesmen. We owned the regular, large, "adult" Encyclopedia Britannica consisting of 24 telephone-book-sized faux leather volumes that looked like something from Winston Churchill's library, along with the Britannica Junior -- the fire engine red, age-appropriate set for the youngsters herein shown -- and the World Book Encyclopedia (which was actually my favorite and the one I used the most). Yes, we had three full integral sets of encyclopedias along with the multi-volume Pictorial Encyclopedia of American History, a nifty and colorful little set I used quite a bit. This is not to mention the annual updated supplemental yearbooks to the regular encyclopedias, an imperfect solution to the obvious fact that encyclopedia sets fell out of date but were too immense to redo and reissue very often. It was also a nice little scheme to get a continuous income flow for the publishers. We also subscribed to the annual science yearbooks.
So, yeah we had a rock solid 20-foot, hundreds-of-pounds-weighing fortress wall 'o knowledge that might also serve as a load-bearing column or wall in a pinch. It was impressive then but may not so much now, as it could all fit on one thumb drive, I'm sure.
It was always a novelty when the supplements arrived by post in sturdy cardboard mailing boxes and smelled like the fine Corinthian leather interior of a new car when you tore open the package.