Study Guides on Images of Liberty and Power: Washington and Napoleon in their Studies (Indianapolis: Liberty Fund, 2010).

The Rights of the British Colonies Asserted and Proved (Boston & London: J. Almon, 1764).

The Philosophical Works of David Hume. Including all the Essays, and exhibiting the more important Alterations and Corrections in the successive Editions by the Author. In Four Volumes. (Edinburgh: Adam Black and William Tait, 1826). Vol. 1.

Popular Government. Four Essays, 3rd edition (London: John Murray, 1886).

Study Guides on Images of Liberty and Power: The Divine Right of Kings or Regal Tyranny? (Hobbes and Lilburne) (Indianapolis: Liberty Fund, 2010).

The Subjection of Women (London: Longmans, Green, Reader, and Dyer, 1878). 4th edition.

The Divine Comedy of Dante Alighieri. The Italian Text with a Translation in English Blank Verse and a Commentary by Courtney Langdon, vol. 1 (Inferno) (Cambridge: Harvard University Press, 1918).

Fifteen Sonnets of Petrarch, selected and translated by Thomas Wentworth Higgiinson (Boston: Houghton Miflin & Co., 1903).

Shakespeares Comedies, Histories, and Tragedies, being a Reproduction in Facsimile of the First Folio Edition 1623 from the Chatsworth copy in the possession of the Duke of Devonshire, K.G. with an Introduction and Census of Copies by Sidney Lee (Oxford: At the Clarendon Press, 1902).

Appendix to the Black Book: An Exposition of the Principles and Practices of the Reform Ministry and Parliament: the Church and the Dissenters; Catastrophe of the House of Lords; and Prospects for Tory Misrule: with tables of ecclesiastical and election statistics and corrections of former editions of the Black Book. By the Original Editor. (London: Effingham Wilson, 1834).