The entire title is actually Spaghetti Westerns: The Good, the Bad and the Violent a Comprehensive Illustrated Filmography of 558 Films.
This mammoth work by Thomas Weisser receives not much love from Italian Western aficionados. Those in the know say it is rife with mistakes, and those in the know may know best, but to this reader, a minor fan of the genre, I have not encountered any discrepancies in the titles I’ve viewed. Keep in mind, Spaghettis aren’t my main viewing choice, but I do watch a few a month and thus far haven’t been steered wrong by this volume.
Make of the reservations what you will, I have found the Top Ten Lists in the back of the book interesting viewing.