That’s the not terribly helpful note in the British Library catalogue for the 1864 Klopp edition of Leibniz’s Werke. Back when the British Library used to be in the British Museum, there was a catalogue entry for books that had been destroyed by bombing in the Second World War. Maybe this is the reason. According to Riley (Leibniz, Political Writings, p. 241) this is “the best edition of his historical and political writings”, though Riley wrote that before some of the Sämliche Schriften und Briefe division that deals with his political writings were published. The full title of the Klopp edition says it is based on his handwritten Nachlass from the Hanover library. I can’t find another library in London that has it.
Now finding the Sämliche Schriften und Briefe is easier (there is also a version online), but locating a reference made to the Klopp edition within it isn’t going to be straight-forward. The relevant division of Sämliche Schriften und Briefe has six volumes published so far, with a draft of the seventh online. But those only take us up to 1699, so Leibniz had another seventeen years of life left. The published volumes have between 700 and 1000 pages each. And this is only one aspect of his work – the philosophical, mathematical, historical and scientific writings are in separate divisions, along with three divisions of correspondence.
Another challenge: Leibniz wrote a dialogue about the position of territorial rulers within the Empire in 1677, entitled Entrétiens de Philarete et d’Eugène. Maria Roza Antognazza’s recent book, Leibniz: An Intellectual Biography (Cambridge: Cambridge University Press, 2009) notes that the dialogue went through sixteen different editions “each successively adapted to constantly changing political conditions” (p. 206).