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:In autopsy series, it was found 5–86 % of cases overall (Bonvini et al. 2008; Canyigit et al. 2009; Ferreira et al. 1991; Lazoura et al. 2010; Mohlenkamp et al. 2002; Ozbag et al. 2002; Ozbag and Kervancioglu 2004).
Category: