I just stumbled upon a terrific source of information including FREE full-text books that you can view or download in a variety of formats, usually including PDF… the catch is the books are old-- but hey, so is railroading… there’s a lot of good useful info out there:
Home of the “Wayback Machine”. I’ve known about the Internet Archive for nearly a decade, but have just (re-?)discovered that they have whole, complete books available online that you can download. All of the material is either out of copyright or donated. They also have other media too if you’re interested. (Myself, I’ve used the site to view other sites “in the past”, i.e., the “Wayback Machine”)
Here, I’ve already done your first book search for you:
(Note that you may want to actually go to the Internet Archive and search for the title or author, as many of these books have multiple printings and/or updated versions available to download)