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Grant, P. R. (1967). "Bill length variability in birds of the Tres Marías Islands, Mexico". Canadian Journal of Zoology. 45 (5): 805–815. Bibcode:1967CaJZ...45..805G. doi:10.1139/z67-092.
"1995 Pulitzer Prize Winners". pulitzer.org. The Pulitzer Prizes — Columbia University. Archived from the original on 15 June 2017. Retrieved 23 August 2017.
"1995 Pulitzer Prize Winners". pulitzer.org. The Pulitzer Prizes — Columbia University. Archived from the original on 15 June 2017. Retrieved 23 August 2017.