I don't know, do you?

On the Improvement of the Understanding

Lectures of Col. R. G. Ingersoll, Volume I Including His Answers to the Clergy, His Oration at His Brother's Grave, Etc., Etc.

Flowers of Freethought (First Series)

Heretics And Heresies From 'The Gods and Other Lectures'

Humboldt From 'The Gods and Other Lectures'

Individuality From 'The Gods and Other Lectures'

The Works of Robert G. Ingersoll, Vol. 06 (of 12) Dresden Edition—Discussions

Christianity Unveiled Being an Examination of the Principles and Effects of the Christian Religion

The Bible: I. Authenticity II. Credibility III. Morality

What I believe

Le grand secret