Edwin Way Teale (2016). “Journey Into Summer: A Naturalist’s Record of a 19,000-Mile Journey Through the North American Summer”, p.39, Pickle Partners Publishing
Thomas Jefferson (1853). “The writings of Thomas Jefferson: being his autobiography, correspondence, reports, messages, addresses, and other writings, official and private : published by the order of the Joint Committee of Congress on the Library, from the original manuscripts, deposited in the Department of State”, p.501