1. Charles Lyell to John William Dawson. Charles Lyell's letters to John William Dawson are in the archives of McGill University, Montreal, Canada, 11 July, 1867
2. On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life;Darwin,1866
3. Life of Sir William E. Logan;Harrington,1883
4. Eozoön canadense “the dawn animal of Canada”;O’Brien;Isis,1970
5. Books and the Sciences in History,2000