Diagnostic differences in psychogeriatric patients in London and New York: United Kingdom-United States diagnostic project.
Copeland JR, Kelleher MJ, Kellett JM, Gourlay AJ, Barron G, Cowan DW, De Grouchy J, Gurland BJ, Sharpe L, Simon R, et al. Can Psychiatr Assoc J. 1974 Jun; 19(3):267-71.