APA (7th ed.) Citation

Walpole, H., & Lewis, W. S. (1926). A selection of the letters of Horace Walpole. Harper.

Chicago Style (17th ed.) Citation

Walpole, Horace, and W. S. Lewis. A Selection of the Letters of Horace Walpole. New York: Harper, 1926.

MLA (9th ed.) Citation

Walpole, Horace, and W. S. Lewis. A Selection of the Letters of Horace Walpole. Harper, 1926.