Porter, Theodore (2004). Karl Pearson. Princeton: Princeton University Press. p. 1080. ISBN 0-691-11445-5. See the Pearson Papers (ref. 900) at UCL Charlotte
Park, Pennsylvania: Penn State University Press. ISBN 978-0-271-03742-4. Pearson, Drew (20 October 1954). "Washington Merry-Go-Round". Prescott Evening