Article subtitle is "A long-lost text by the ancient Greek mathematician shows that he had begun to discover the principles of calculus." This has been known for several decades, ever since Heiberg transcribed some of the text (I don't know how much), per the article.
I refer you to The History of the Calculus and Its Conceptual Development, a 1949 book by Carl B. Boyer, reprinted by Dover Publications [ISBN 0486605094]. Boyer writes several pages about Archimedes' method of exhaustion, notions of the infinitesimal, and so on. The main footnote reads:
For the works of Archimedes in general, see Heiberg, Archimedes opera omnia and T. L. Heath, The Works of Archimedes. For Archimedes' Method, see T. L. Heath, The Method of Archimedes, Recently Discovered by Heiberg; Heiberg and Zeuthen, "Eine neue Schrift des Archimedes"; and Smith, "A Newly Discovered Treatise of Archimedes."
Boyer is clearly using Heiberg's work on the Archimedes Palimpsest.
I refer you to The History of the Calculus and Its Conceptual Development, a 1949 book by Carl B. Boyer, reprinted by Dover Publications [ISBN 0486605094]. Boyer writes several pages about Archimedes' method of exhaustion, notions of the infinitesimal, and so on. The main footnote reads:
For the works of Archimedes in general, see Heiberg, Archimedes opera omnia and T. L. Heath, The Works of Archimedes. For Archimedes' Method, see T. L. Heath, The Method of Archimedes, Recently Discovered by Heiberg; Heiberg and Zeuthen, "Eine neue Schrift des Archimedes"; and Smith, "A Newly Discovered Treatise of Archimedes."
Boyer is clearly using Heiberg's work on the Archimedes Palimpsest.