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- Lodge, John, -17963
- Longman, Rees, Orme, Brown, and Green3
- Lusardi, Barbara A3
- Lynch, F. C. C. (Francis Christopher Chisholm), 1884-3
- Machamer, J.F.3
- Mangum, A. W.3
- Marshall, R. B. (Robert Bradford), 1867-19493
- Maryland Geological Survey3
- McEvoy, James, 1862-3
- McGee, W J, 1853-19123
- McPherson, James Birdseye, 1828-18643
- Meyer, G.N3
- Minnesota Transfer Board of Trade.3
- Minnesota. Division of Game and Fish3
- Mitchell, S. Augustus (Samuel Augustus), 1792-1868, cartographer.3
- Mortier, Corneille3
- Morton, Robert H.3
- Münster, Sebastian, 1489-15523
- Nathan, H.D. (Geologist)3