Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:It performs three fundamental functions: it binds a spermatozoon—thus preventing interspecies fertilization; it induces the acrosome reaction of the spermatozoon; and, finally, immediately after fertilization, it prevents polyspermy (Baker et al. 2000; Bleil and Wassarman 1990; Herrler and Beier 1999; Serrano and Garcia-Suarez 2001;Thaler and Cardullo 2002; Yanagimachi 1994; Zhao and Dean 2002).
Category: