Charles Darwin (1840). “Journal of Researches Into the Geology and Natural History of the Varoius Countries Visited by H.M.S. Beagle, Under the Command of Captain Fitzroy from 1832 to 1836 by Charles Darwin”, p.557
"Richard Di Natale elected unopposed as new Greens leader after Christine Milne resigns - as it happened" by Daniel Hurst, www.theguardian.com. May 6, 2015.