and some notes on technique for myself later.
I drill two holes through all but the top and bottom cover of the stack of books. Then I run a wire through and secure it.
I have learned to wait a day or so to let the contents settle, because sometimes the drilling puffs up the pages.
Then I glue the front and back pages to cover the wire.
I have discovered the technique works best if the books are slim enough for the drill to go all the way through. Also its best if I stack them mostly straight. while asymmetry is pleasing, my own natural haphazard style means if I try to drill straight they end up slightly asymmetric anyway. If I stack them asymmetrically initially they get too asymmetric (e.g. Karl Marx Capital).I'm considering backing the bottom one with felt, or polar fleece, since I have some in the cupboard. Necessity is the mother of invention.