(en) Richard Allen Schwarzlos, The Nation's Newsbrokers : The Rush to Institution, from 1865 to 1920, Northwestern University Press, 1990 (ISBN978-0-8101-0819-6) [lire en ligne] p. 167
(en) Richard Allen Schwarzlos, The Nation's Newsbrokers : The Formative Years : From Pretelegraph to 1865, Northwestern University Press, 1989 (ISBN978-0-8101-0818-9) [lire en ligne] p. 93
(en) Richard Allen Schwarzlos, The Nation's Newsbrokers : The Formative Years : From Pretelegraph to 1865, Northwestern University Press, 1989 (ISBN978-0-8101-0818-9) [lire en ligne] p. 125