In many jurisdictions, copyright lasts for decades after publication. Therefore, downloading a scanned PDF from a random file-sharing site may infringe on the rights of the original publishers or photographers. However, there are legitimate avenues for finding free content:
It looks like you're interested in the Sonnenfreunde Sonderheft series, which is a well-known German naturist (FKK) magazine collection that has been around since at least the
Sonderheft Magazine 156 is a treasure trove of information for anyone interested in sustainable living and renewable energy. Some of the topics covered in this issue include: