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:…the previous reports on the toxicokinetics of p-DCB in animals, in which the major route of excretion is the urine (Hawkins et al. 1980; Klos and Dekant 1994; Hissink et al. 1996, 1997), the major route for the elimination of p-DCB in humans was assumed to be metabolism and then excretion in urine.
Category: