 Indeed one quickly sees a wide variety of different interpretations of the correspondence principle emerging in the physics literature—a variety of interpretations that persists to this day. Hence, it is important to distinguish Bohr’s own views on the correspondence principle from what the correspondence principle came to mean to the broader physics community (for a detailed account of how the correspondence principle drove research and discussions in this period, see Jähnert 2019). Both Hendrik Kramers and John van Vleck, for example, used and extended the term “correspondence principle” to cover a wide range of correspondence-type arguments that were important in the development of quantum mechanics (see, for example, Duncan and Janssen 2007; 2019).