1. John D. Norton, Archive for History of Exact Science, 45, 17 (1992).
2. Albert Einstein, quotation excerpted from Norton’s article, preceding reference.
3. Gunnar Nordström, Annalen der Physik, 40, 856 (1913).
4. Christopher Ray, The Evolution of Relativity (Adam Hilger, Bristol and Philadelphia, 1987).
5. Albert Einstein and Adriaan Fokker, Annalen der Physik, 44, 321 (1914).