Here are links to some articles about early spay/neuter.
http://www.columbusdogconnection.com/PedSpayNeuter.htm
http://www.cvm.uiuc.edu/ceps/ivb/spay-neu.htm
Aronsohn MG and Faggella AM: Surgical techniques for neutering 6- to 14week-old kittens. J Ain Vet Med Assoc 202:53, 1993, A study describing the surgical techniques and considerations for early neutering in 96 kittens.
Faggella AM all(] Aronsohn MG Anesthetic techniques too neutering 6 to 14 weekold kittens. I Ain Net Med Assoc 202:56, 1993. A study comparing four anesthetic protocols used for early neutering in kittens
Grandy IL and Dunlop Cl: Anesthesia of pups and kittens. J All) Vet Med Assoc 198:1244, 1991. An article reviewing physiology, pharmacokinetics, and anesthetics used in pediatric patients.
Houlton JEF and McGlennon NJ: Castration and physeal closure in the cat. Vet Rec 131:466, 1992. A pilot study demonstrating delayed physeal closure in two cats castrated at 28 weeks of age.
Saluted KII, Olson PN, and Bloomberg MS: Elective, gonadectomy in the dog A review. J Am Vet Med Assoc 198:1183, 1991.
A review of the physiology of puberty and the current knowledge and potential effects of gonadectomy.
Salmeri KR, Bloomberg MS, Scruggs SL, et al: Gonadectomy in immature dogs: Effects on skeletal, physical, and behavioral development. J Am Vet Med Assoc 198:1193, 1991. Results of a study investigating the developmental effects of early neutering in (logs.
Stone KA, Cantrell CC, and AAarp AIM (A an arid uterus In Sldmer D Textbook of Small Amaral Surgery. Volume 2. Philadelphia, WB Saunders Co, 1993, p 1293. Description of surgical diseases and techniques of the ovaries and uterus.Theran P: Early-age neutering of dogs and cats. J Am Vet Med Assoc 202: 914, 1993. A review of surgical and anesthetic techniques for neutering 6- to I 14-week-old puppies and kittens.