Vaihinger an Albert Einstein, Halle, 23.5.1920, Ts. mit eU, Regest in: [https://einsteinpapers.press.princeton.edu/vol10-doc/643]Regest (Zitat): „Asks permission to publish Einstein’s Leyden lecture [Raum und Zeit in der neueren Physik] delivered on 19 May in his journal Annalen der Philosophie. He plans to devote its next issue to Einstein’s achievements (“Einstein-Heft”). Moritz Schlick cannot attend the “Als-Ob” conference […], but offered a paper on the relationship between relativity and philosophy.“