As Alex McDonald notes in this support request, Google has recently banned the old Usenet groups comp.lang.forth and comp.lang.lisp from the Google Groups system. "Of specific concern is the archive. These are some of the oldest groups on Usenet, and the depth & breadth of the historical material that has just disappeared from the internet, on two seminal programming languages, is huge and highly damaging. These are the history and collective memories of two communities that are being expunged, and it's not great, since there is no other comprehensive archive after Google's purchase of Dejanews around 20 years ago." Perhaps Google can be convinced to restore the content, but it also seems that some of this material could benefit from a more stable archive.