Sleeplessness and Circadian Rhythm Disorder. eMedicine World Medical Library from WebMD. Retrieved on 2006- 06-04.
WHO Technical meeting on sleep and health - meeting report, accessed August 12 2006.
Weitzman E.D., Czeisler CA. “Delayed sleep phase syndrome: a chronobiological disorder with sleep-onset insomnia”. Archives of General Psychiatry 1981, 38: 737- 746.
Ancoli-Israel S, Schnierow B, Kelsoe J, Fink R. “A pedigree of one family with delayed sleep phase syndrome.”. 2001, Chronobiology International 18 (5): 831–840.
Evolution of a length polymorphism in the human PER3 Gene, Nadakarni et al. JOURNAL OF BIOLOGICAL RHYTHMS / December 2005.
Boivin, D.B. et al. Non-24-hour sleep–wake syndrome following a car accident Neurology 2003;60:1841-1843