The International Union for Conservation of Nature has published World at Night, Preserving natural darkness for heritage conservation and night sky appreciation.
This looks like an excellent general guide to global light pollution issues. It is 160 pages so I’ve not read it yet, but the page (7) on amateur astronomy and stargazing is particularly good. I especially like the opening sentence.
Thanks to John Barentine, one of the authors, for announcing this.
https://portals.iucn.org/library/sites/library/files/documents/PAG-033-En.pdf