Matthew, Henry Colin Gray et al., editors. Oxford Dictionary of National Biography. http://www.oxforddnb.com/.
Charles Knowlton
Standard Name: Knowlton, Charles
Timeline
Texts
Chandrasekhar, Sripati et al. "A Dirty Filthy Book": The Writings of Charles Knowlton and Annie Besant on Reproductive Physiology and Birth Control and an Account of the Bradlaugh-Besant Trial. University of California Press, 1981.
Bradlaugh, Charles et al. “Publishers’ Preface”. Fruits of Philosophy: An Essay on the Population Question, 2nd ed., Freethought Publishing, 1877, pp. 3-7.