Mr. Broad’s interesting article in the July Mind on “A General Notation for the Logic of Relations” attributes to me (for what reason I cannot guess) a number of notations employed in Principia Mathematica. As far as my memory serves me, all these were invented by Dr. Whitehead, who, in fact, is responsible for most of the notation in that work. My original notation, before he came to my assistance, may be found in Peano’s Revue de Mathématiques, vols. vii and viii.

Bertrand Russell

Mind, n.s., vol. 28, no. 119 (Jan 1919), 124