Alfred Russel Wallace (1853). “A Narrative of Travels on the Amazon and Rio Negro: With an Account of the Native Tribes, and Observations on the Climate, Geology, and Natural History of the Amazon Valley”, p.83, London : Reeve and Company
"David Attenborough: 'I have been in a vehicle that was charged by a rhinoceros, and that was tiresome'". Interview with Kate Kellaway, www.theguardian.com. October 30, 2010.
"Sir David Attenborough reveals a pacemaker and knee replacement surgery have given him a 'new lease of life'" by Claire Murphy, www.mirror.co.uk. November 6, 2016.