Epictetus, Marcus Aurelius, Lucius Annaeus Seneca (2016). “Stoic Six Pack: Meditations of Marcus Aurelius, Golden Sayings, Fragments and Discourses of Epictetus, Letters from a Stoic and The Enchiridion”, p.25, Enhanced Media Publishing
John Cotton Dana's remarks on a quotation suitable for inscription on a new building at Newark State College, Union, New Jersey (1912) as quoted in "The New York Times Book Review" (p. 55.), March 5, 1967.
Lord Philip Dormer Stanhope Chesterfield, Philip Dormer Stanhope Earl of Chesterfield (1855). “The Works of Lord Chesterfield: Including His Letters to His Son, Etc : to which is Prefixed, an Original Life of the Author”, p.313