Lieber Francis. The Life and Letters of Francis Lieber. Thomas Sergant Perry (ed.). Boston: James R. Osgood & Co., 1882.

Litchfield Henrietta (ed.). Emma Darwin. A Century of Family Letters, 1792–1896. New York: D. Appleton and Company, 1915.

Lowenthal David. George Perkins Marsh. Prophet of Conservation. Seattle and London: University of Washington Press, 2003.

Lyell Charles. Principles of Geology. London: John Murray, 1830 (1832, second edition).

______. Life, Letters and Journals of Sir C. Lyell. Katharine Murray Lyell (ed.). London: John Murray, 1881.

Lynch John. Simón Bolívar. A Life. New Haven and London: Yale University Press, 2007.

MacGregor Arthur. Sir Hans Sloane. Collector, Scientist, Antiquary, Founding Father of the British Museum. London: British Museum Press, 1994.

McKusick James C. Coleridge and the Economy of Nature // Studies in Romanticism, vol. 35, 1996

Madison James. The Papers of James Madison: Presidential Series. Robert A. Rutland et al. (ed.). Charlottesville: University of Virginia Press, 1984–2004.

______. The Papers of James Madison: Secretary of State Series. Robert J. Brugger et al. (ed). Charlottesville: University of Virginia Press, 1986–2007.

______. The Papers of James Madison: Retirement Series. David B. Mattern et al. (ed.). Charlottesville: University of Virginia Press, 2009.

Marrinan Michael. Romantic Paris. Histories of a Cultural Landscape, 1800–1850. Stanford: Stanford University Press, 2009.

Marsh George Perkins. The Camel. His Organization Habits and Uses. Boston: Gould and Lincoln, 1856.

______. Report on the Artificial Propagation of Fish. Burlington: Free Press Print, 1857.

______. Lectures on the English Language. New York: Charles Scribner, 1861.

______. Life and Letters of George Perkins Marsh. Caroline Crane Marsh (ed.). New York: Charles Scribner’s and Sons, 1888.

______. Catalogue of the Library of George Perkins Marsh, Burlington: University of Vermont, 1892.

______. So Great A Vision: The Conservation Writings of George Perkins Marsh. Stephen C. Trombulak (ed.). Hanover: University Press of New England, 2001.

______. Man and Nature; or, Physical Geography as Modified by Human Action, 1864, facsimile of first edition. David Lowenthal (ed.). Seattle and London: University of Washington Press, 2003.

Merseburger Peter. Mythos Weimar. Zwischen Geist und Macht. Munich: Deutscher Taschenbuch Verlag, 2009.

Meyer-Abich Adolph. Alexander von Humboldt. Bonn: Inter Nationes, 1969.

Miller Char. Gifford Pinchot and the Making of Modern Environmentalism. Washington: Island Press, 2001.

Miller Sally M. (ed.). John Muir. Life and Work. Albuquerque: University of New Mexico Press, 1996.

______. John Muir in Historical Perspective. New York: Peter Lang, 1999.

Minguet Charles. Las relaciones entre Alexander von Humboldt y Simón de Bolívar // Bolívar y Europa en las crónicas, el pensamiento político y la historiografía. Alberto Filippi (ed.). Caracas: Ediciones de la Presidencia de la República, vol. 1, 1986.

Mommsen Wolfgang J. 1848. Die Ungewollte Revolution. Frankfurt: Fischer Verlag, 2000.

Moreno Yánez Segundo E. (ed.). Humboldt y la Emancipación de Hispanoamérica. Quito: Edipuce, 2011.

Morgan S. R. Schelling and the Origins of his Naturphilosophie // Romanticism and the Sciences. Andrew Cunningham and Nicholas Jardine (eds.). Cambridge: Cambridge University Press, 1990.

Moritz Carl Philip. Carl Philip Moritz. Journeys of a German in England in 1782. Reginald Nettel (ed.). London: Jonathan Cape, 1965.

Mueller Conrad. Alexander von Humboldt und das preussische Königshaus. Briefe aus dem Jahre 1835–1857. Leipzig: K. F. Koehler, 1928.

Muir John. Manuscript Journal: The “thousand mile walk” from Kentucky to Florida and Cuba, September 1867–February 1868 // Online collection of John Muir journals. Holt-Atherton Special Collections, University of the Pacific Library. Stockton, California. © 1984 Muir-Hanna Trust.

______. Manuscript ‘Sierra Journal’, vol. 1: Summer 1869, notebook, circa 1887, John Muir Papers, Series 3, Box 1: Notebooks. Holt-Atherton Special Collections, University of the Pacific Library. Stockton, California. © 1984 Muir-Hanna Trust.

______. ‘Sierra Journal’, vol. 1: Summer 1869, typescript, circa 1910, John Muir Papers, Series 3, Box 1: Notebooks. Holt-Atherton Special Collections, University of the Pacific Library. Stockton, California. © 1984 Muir-Hanna Trust.

______. Manuscript Journal, ‘World Tour’, pt. 1, June – July 1903, online collection of John Muir journals. Holt-Atherton Special Collections, University of the Pacific Library. Stockton, California. © 1984 Muir-Hanna Trust.

______. The Wild Parks and Forest Reservations of the West // Atlantic Monthly, vol. 81, January 1898.

______. Our National Parks. Boston and New York: Houghton Mifflin Company, 1901.

______. My First Summer in the Sierra. Boston and New York: Houghton Mifflin Company, 1911.

______. The Yosemite. New York: Century Co., 1912.

______. The Story of my Boyhood and Youth. Boston and New York: Houghton Mifflin Company, 1913.

______. A Thousand-Mile Walk to the Gulf. William Frederic Badè (ed.). Boston and New York: Houghton Mifflin Company, 1916.

______. Life and Letters of John Muir. William Frederic Badè (ed.). Boston and New York: Houghton Mifflin Company, 1924.

Mumford Lewis. The Brown Decades. A Study of the Arts in America, 1865–1895. New York: Harcourt, Brace and Company, 1931.

Murchison Roderick Impey. Address to the Royal Geographical Society of London, 23 May 1859 // Proceedings of the Royal Geographical Society of London, vol. 3, 1858–1859.

______. Life of Sir Roderick I. Murchison. Archibald Geikie (ed.). London: John Murray, 1875.

Myers A. C. Narratives of Early Pennsylvania, West Jersey, and Delaware, 1630–1707. New York: Charles Scribner’s and Sons, 1912.

Myerson Joel. Emerson’s Thoreau: A New Edition from Manuscript // Studies in American Renaissance, 1979.

Nash Roderick. Wilderness and the American Mind. New Haven and London: Yale University Press, 1982.

Nelken Halina. Alexander von Humboldt. Bildnisse und Künstler. Eine dokumentierte Ikonographie. Berlin: Dietrich Reimer Verlag, 1980.