Clemen, Wolfgang, English Tragedy before Shakespeare, Methuen, 1961, pp. 100—12.

This is an analysis of the long set speeches in The Spanish Tragedy. Clemen shows Kyd's originality in integrating these speeches with the structure of the plot and in presenting them in a more dramatic fashion than their Senecan models.

Freeman, Arthur, Thomas Kyd: Facts and Problems, Clarendon Press, 1967.

This is the most comprehensive account of Kyd's life and works. It includes detailed discussions of the date and sources of The Spanish Tragedy, as well as its style, structure, stage history, parodies, textual additions, and critical reception.

Harbage, Alfred, "Intrigue in Elizabethan Tragedy," in Essays on Shakespeare and Elizabethan Drama, in Honor of Hardin Craig, edited by Richard Hosley, University of Missouri Press, 1962, pp. 37—44.

Harbage argues that one of Kyd's distinctive and influential achievements was his introduction into tragedy of the element of intrigue, in...