> They were printed on a long paper then folded onto itself which creates the pages and then stitched in the middle, the folds are then are cut on the sides to free the pages.

Ah, the memories... I recall some of the vintage math textbooks from my high school's library (one of the older teachers had died and willed his personal library to the school, about 12k books). I must have been the first one to actually read some algebra texts because about half of their pages was improperly separated.