Isabel Meirelles’s “Design for Information” points to the following two seminal books on textual visualization:
Readings in Information Visualization: Using Vision to Think by Stuart K. Card.
Graphs, Maps, Trees: Abstract Models for Literary History by Franco Moretti
In addition, these are some of the case studies/examples that she mentions:
Wordle (http://www.wordle.net)
Google Books Ngram Viewer (http://books.google.com/ngrams)
[Photomedia Forum post by T.Neugebauer from Aug 14, 2015 ]