N: 1. Peter Gay, The Enlightenment: An Interpretation, vol. 2, The Science of Freedom (New York: Knopf, 1969), 345-49.
B: Gay, Peter. The Science of Freedom. Vol. 2 of The Enlightenment: An Interpretation. New York: Knopf, 1969.
NOTE: The format of citations for multivolume works depends on a number of variables, including whether all volumes were published in the same year, whether individual volumes have a single author or multiple authors, whether the set has an editor, whether each volume has a unique title, and whether you wish to cite the work as a whole or only a single volume of the work. If you are unsure of how to cite a multivolume source you've used, it is best to consult the Manual, 14.116-14.122.