Because these are vintage publications, "links" typically refer to either digital archives or listings on collector marketplaces.
The (Friends of the Sun) series was primarily published by Sonnenfreunde-Verlag in Hamburg. sonnenfreunde sonderheft magazine 23 link
Searching for the link often leads to a mix of vintage collector archives and digital download platforms. This specific issue is part of a historic series of German naturist (FKK - Freikörperkultur ) publications that date back to the mid-20th century. Where to Find Issue 23 Because these are vintage publications