- Works, Volume 2
- The Religion of Abraham Lincoln: Correspondence Between General Charles H. T. Collis and Colonel Robert G. Ingersoll
- Some Mistakes of Moses
- Die götter
- Wit, Wisdom, Eloquence, and Great Speeches of Col. R. G. Ingersoll: Including Eloquent Extracts, Witty, Wise, Pungent, Truthful Sayings and Full Reports of the Great Speeches of This Celebrated Man, T