"The HathiTrust Digital Map is an interactive map which allows you to browse and explore the 14 million volumes in the HaithTrust's repository of digitized texts... The Library of Congress Classification system categorizes books into different broad subjects and then by sub-classes within each of these subjects. The HathiTrust Digital Map uses an entirely different method of classification. On this interactive maps texts are organized by the similarity in the vocabulary of individual texts."
Source: " A Map of all the Books," Map Mania, October 12, 2018, http://googlemapsmania.blogspot.com/2018/10/a-map-of-all-books.html