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:Data were simulated with the mvrnorm module of the MASS package (version 7.3-6; Venables & Ripley, 2002) and version 2.11.1 of R (R Development Core Team, 2010).
Category: