When referencing in the Chicago referencing style, for multiple works by the same author, alphabetise all entries by title in your bibliography, and replace the author name with a 3-em dash (—) in all entries after the first, for example:

Burn, Andrew. R. The Romans in Britain : An Anthology of Inscriptions : With Translations and a Running Commentary. 2nd ed. Oxford: Blackwell, 1969.

—, Agricola and Roman Britain. New York: Collier Books, 1962.