References:
Background artwork on page 1 based on Emmy Lischke, Abendliche Stimmung (ca. 1900)
Background artwork on page 1 based on photograph M37 of Caltech project ›Two Micron All Sky Survey‹ (2MASS)
For context cf. Heyer/Vogl, DJIL.de. No. 00062, December 2021.