Easton J, 1999, Nathaniel Kleitman. The University of Chicago Medical Center Press Release, Au¬gust 16 (available at: http://www.uchospitals.edu/news/1999/19990816-kleitman.html)
Lamberg L, 2004, The Student, the Professor and the Birth of Modern Sleep Research, [in:] Medicine on the Midway (available at: www.uchospitals.edu/pdf/uch_006319.pdf)
Reed C, 1999, Nathaniel Kleitman. The Guardian Obituaries, August 25 (available at: www.guard- ian.co.uk)
Rosbash M, Takahashi JS, 2006, Going to Extremes [in:] Time Matters: Biological Clockworks. Howard Hughes Medical Institute, October 21 (available at: http://www.hhmi.org/biointeractive/museum/exhibit00/03_l.html)
Siegel JM, 2001, A Tribute to Nathaniel Kleitman. Arch Ital Biol; 139 (1-2), 3-10 (available at: http://www.npi.ucla.edu/sleepresearch/Kleitman/Kleitman.htm)
Shumard T, 2000, In Memoriam Nathaniel Kleitman. European Society of Sleep Technologists Newsletter, p. 3 (available at: http://esst.org/newsletter2000.htm)
Stickgold R, 2003, The Discovery of REM Sleep. Sleepmatters, Vol. 5, Issue 1, National Sleep Foundation (available at: http://www.sleepfoundation.org/sleepmatters)