1. J. Piaget, “Play, Dreams, and Imitation in Childhood,” W. W. Norton & Co Inc., 1962.
2. K. Grammer, K. Kruck, and M.Magnusson, “The Courtship Dance: Patterns of Nonverbal Synchronization in Opposite-Sex Encounters,” J. of Nonverbal Behavior, Vol.22, No.1, pp. 3-29, 1998.
3. T. Perper, “Sex signals,” The Biology of Love, ISI Press, 1985.
4. C. Perfetti, “Condotte terapeutiche per la rieducazione motoria dell’emiplegico,” Libreria Scientifica gia Ghedini s.r.l. Milano, 1986.
5. C. Perfetti, “La rieducazione motoria dell’emiplegico,” Libreria Scientifica gia Ghedini s.r.l. Milano, 1979.