1 Provine, R “Laughter punctuates speech: Linguistic, social and gender contexts of laughter”. Ethology 1993, 95:291-298.

2  Eibl-Eibesfeldt, I. Etologia – Introducción Al Estudio Comparado Del Comportamiento. Ediciones Omega, S.A, Barcelona. Irnäus Eibl-Eibesfeldt, 1974: 466-612.

3 Concar, D. “Primal mirth is no laughing matter”  New Scientist, 2 May 1998.

4 Knutson, B, Burgdorf, J and Panksepp, J.  “Anticipation of Play Elicits High-Frequency Ultrasonic Vocalizations in Young Rats.” Journal of Comparative Psychology 1998; 112: 65-73.

5 Fried I, Wilson, CL, MacDonald KA, and Behnke EJ. “Electric current stimulates laughter.” Nature 1998 Feb 12;391(6668):650

6 Blakemore SJ, Wolpert DM, Frith CD. – “Central  cancellation of self-produced tickle sensation”. Nature Neuroscience 1998 Nov;1(7):635-40.

7 Gardner, H, Ling, PK, Flamm, L and Silverman, J. “Comprehension and appreciation of humorous material following brain damage.” Brain 1975, 98: 399-412.

8 Shammi P & Stuss DT – “Humor appreciation: a role of the right frontal lobe”. Brain 1999  Apr;122 (Pt 4):657-66 .

9 Daigneault S, Braun CM, and Montes JL  “Hypothalamic hamartoma: detailed presentation of a case.” Encephale 1999 Jul-Aug;25(4):338-44