1. In H. A. Lorentz, A. Einstein, H. Minkowski, Das Relativitätsprinzip,Fortschritte der mathematischen Wissenschaften 2, mit Anmerkungen von A. Sommerfeld und Vorwort von O. Blumenthal (Leipzig: B. G. Teubner, 1913), p. 23 (Pais translation).
2. H. A. Lorentz, “Het relativiteitsbeginsel. Voordrachten in Teyler’s Stichtung,” Archives Musée Teyler 2 (1914): 26. See the outstanding historical study by Jozsef Illy, “Einstein Teaches Lorentz, Lorentz Teaches Einstein. Their Collaboration in General Relativity, 1913–1920,” Archive for History of Exact Sciences 39 (1989): 272, who comments, “Lorentz distinguishes the existence of a state of motion from its observability—a distinction void of meaning according to Einstein.”
3. H. A. Lorentz, “Considérations élémentaires sur le principe de relativité,” Revue générale des Sciences 25 (1914): 179ff, in H. A. Lorentz, Collected Papers, ed. P. Zeeman and A. D. Fokker ( The Hague: Martinus Nijhoff, 1934 ), 7: 165.
4. Albert Einstein, Äether und Relativitätstheorie ( Berlin: Julius Springer Verlag, 1920 ), p. 7.
5. Albert Einstein, "The Problem of Space, Ether, and the Field in Physics" [Mein Weltbild, 1934], in Ideas and Opinions, trans. Sonja Bargmann (New York: Crown Publishers, 1954), p. 281. So also Tetu Hirosige, "Origins of Lorentz' Theory of Electrons and the Concept of the Electromagnetic Field," Historical Studies in the Physical Sciences 1 (1969): 197