@book{Four,
    Author = "Sir Arthur Conan Doyle",
    Title = "The Sign of Four",
    Month = 2,
    Year = 1890,
    URL = "https://sherlock-holm.es/stories/pdf/a4/1-sided/sign.pdf",
}
@book{Jekyll,
    Author = "Robert Louis Stevenson",
    Title = "The Strange Case of Dr. Jekyll and Mr. Hyde",
    Year = 1886,
    Month = 1,
    Day = 5,
    URL = "https://www.planetebook.com/free-ebooks/the-strange-case-of-dr-jekyll.pdf",
}