1. “...the nature of the metric field...is essentially one and therefore absolutely determined...in it the aprioristic essence of the space-time structure is expressed” (Weyl 1923b, p.45)
2. Scheibe 1999, VIII.3 (Newton/Cartan theory of gravitation)
3. Scheibe 1997b, IV. 1–3
4. First published as Scheibe 1982c. The completion of this paper was made possible by a Visiting Fellowship at the Center for Philosophy of Science at the University of Pittsburgh. The author wants to express his gratitude to the chairman and the director of the Center, Professor A. Grünbaum and Professor L. Laudan, for the kind invitation and generous hospitality.
5. Bourbaki 1968, Ch. IV