The columns below have been divided between print and electronic for ease of access. Do not make the mistake of thinking that because something is easier to access (i.e. online) it is more important (in fact, the opposite is often true).
Note that this work is often cited as the quintessential introduction to the study of the Hebrew book, and some of it still stands, but many of its chapters and notes have been superceded by work produced in the 100+ years that followed its publication.
An important - and recent - overview of the field.