There are no authentic, rare occult books that's publicly accessible. No prolific, historic grimoire was written by who it says it was written buy; therefore, most grimoires are fraudulent while canon. If you don't understand that most of occultism is based on fiction, you shouldn't be trying to buy rare occult books. My grimoires are authentic because you can show it was written by me. Anyone's magical journal is authentic; however, who's going to get your personal historical artifacts when you die. For me, it certainly won't be a weirdo on the Internet. Is a person who sells their translation of the Greater Key of Solomon engaging in fraud sense the grimoire is not authentic?