Charles Lyell (1873). “The Geological Evidence of the Antiquity of Man with an Outline of Glacial and Post-tertiary Geology and Remarks on the Origin of Species with Special Reference to Mans First Appearance on the Earth by Charles Lyell”, p.202
Sir Charles Lyell (1845). “Travels in North America, in the Years 1841-2: With Geological Observations on the United States, Canada, and Nova Scotia”, p.15