Benjamin B. Warfield — An Introduction to the Textual Criticism of the New Testament (London: Hodder and Stoughton, 1886).
A primer to the art of textual criticism: the matter of criticism (the manuscripts, versions and fathers, and the causes of variant readings), the methods of criticism (internal and external evidence, genealogy), the praxis of criticism with worked examples, and the history of criticism from Erasmus to Westcott and Hort.