Historical remarks from Klein about Poincaré's note in "Comptes Rendus 146" and in "the origins of relativity".

Klein's reply to Pauli's letter of 4 May, and detailed comments on several passages in the encyclopedia.

Klein's further remarks and suggestions about the encyclopedia article.

Klein's comments on the proofs of Pauli's encyclopedia article.

A few more suggestions from Klein for changes to Pauli's encyclopedia.

Klein's writes about his and Hilbert's view that the specific significance of Einstein's theory is to be found in its physical conception, but that its precise formulation is a purely mathematical problem. He makes further comments about relativity.

Klein writes about the paginated proofs of the article and gives more suggestions.

Klein writes about his discussion with Sommerfeld on the use of Einstein's notation "Lorentz, Amsterdam Verlag, 1916" and about Klein's inability to work on relativity for a year, and his receipt of Pauli's manuscript.

Klein's editorial remarks on Pauli's relativity article : notation, use of Lorentz group and clarity.