Another book on Google: “The Mystical Presence” by Nevin
There is an interesting post by Jonathan Bonomo at Reformed Catholicism on Calvin’s Sacramentology; if you are curious about Calvin’s views on the Sacraments you will be interested in this post. I would like to mention another book I found on Google that used to be nearly as hard to get as Darwell Stone’s text on the Eucharist, and that is The Mystical Presence by John Williamson Nevin. This is very much in a class with Stone’s work in terms of the quality of its writing and research.
I should note, though, that Wipf and Stock has (as they have done with many valuable works) made this text available as a reprint through their site as well. I have this text from them and it is very well done.