References: John Raymond Hazel; Ethel Cole; Elizabeth Kleen; Herbert A. Thorpe; Alice Groff; B. Lieber; Plato; Aristotle; Zeno; Beccaria; Voltaire; Rosseau; Montesquieu; John Stuart Mill; Thomas Huxley; Emile Zola; Paul Adam; Guy de Maupassant; Gustave Le Bon; Anatole France; Robert G. Ingersoll; Ralph Waldo Emerson; Joseph Chamberlain; John Burns; John Ruskin; H.G. Wells; John Morley; Auguste Comte; Eugene Brieux; William Graham Sumner; Remy de Gourmont; Helene Stoecker; Oda Olberg; Ellen Key; Iwan Bloch; Havelock Ellis; Joseph McCabe; George Bernard Shaw; William Bateson; Walter A. Roberts; Abraham Jacobi; Otto Bobsien; James F. Morton Jr.; S. Michelson-Wexler; Stephen Haweis; August Forel; Heinrich Kirsch; Anton von Menger; Bridget C. Peixotto; Mr. and Mrs. S.E. Patersons; Mary Eastman; S. Van Houten; Margaret Warner Morley; William Lee Howard; Ira S. Wile; Prince W. Morrow; W.W. Sanger; Robert Bird Kerr.