^Carnap, R. (1934), "On the Character of Philosophic Problems (Über den Charakter der philosophischen Probleme)," translation by W. M. Malisoff, Philosophy of Science, 1, pp. 5–19.
^ abcA. W. Carus, Michael Friedman, Wolfgang Kienzler, Alan Richardson, Sven Schlotter (eds.), Rudolf Carnap: Early Writings: The Collected Works of Rudolf Carnap, Volume 1, Oxford University Press, 2019, pp. xiii–xiv.
^ abcCite error: The named reference SEP was invoked but never defined (see the help page).
^Richardson, Alan; Isaacson, Dan (1994). "Carnap's Principle of Tolerance". Proceedings of the Aristotelian Society, Supplementary Volumes. 68: 67–83. doi:10.1093/aristoteliansupp/68.1.67. JSTOR4107023.
^Rudolf Carnap (1966), An Introduction to the Philosophy of Science, Basic Books, p. 220.