> You can't grep dead trees.
Those cards are no replacement for literal grep, of course. They were a search across a tiny summary of the contents, albeit a fairly structured one (which is helpful for some searches).
Then download the catalog in PDF form.
Compare the speed with which you can page through 100 pages or more at maximum physical speed which is useful enough visually for you to get enough of a grasp to stop exactly where you need to, when you wouldn't know exactly what to search for in text form anyway.
Trevanian had an anecdote in shibumi about how he had to remove the description of a museum robbery from later editions of an earlier book - the eiger sanction.
I own the first edition of both, obviously.