APA (7th ed.) Citation

Spencer, H., & Duncan, D. (2014). The life and letters of Herbert Spencer (Digitally Print., London 1908.). Cambridge Univ. Press.

Chicago Style (17th ed.) Citation

Spencer, Herbert, and David Duncan. The Life and Letters of Herbert Spencer. Digitally Print., London 1908. Cambridge: Cambridge Univ. Press, 2014.

MLA (9th ed.) Citation

Spencer, Herbert, and David Duncan. The Life and Letters of Herbert Spencer. Digitally Print., London 1908. Cambridge Univ. Press, 2014.