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 was related for females of Bitis nasicornis (Marsh and Glatston, 1974), Crotalus adamanteus (Mebs and Kornalik, 1984), and Calloselasma rhodostoma (Daltry et al.
Category: