James Joseph Sylvester (1870). “The Laws of Verse: Or Principles of Versification Exemplified in Metrical Translations, Together with an Annotated Reprint of the Inaugural Presidential Address to the Mathematical and Physical Section of the British Association at Exeter”, p.119
Charles Darwin (1902). “Charles Darwin: His Life in an Autobiographical Chapter and in a Selected Series of His Published Letters”, p.46, Library of Alexandria