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:Glomus group A, the largest fungal group within Glomeromycota, has been found as both pteridophyte sporophytes and gametophytes, including underground mycoheterotrophic gametophytes (Kovács et al. 2007; Winther and Friedman 2007, 2008, 2009; West et al. 2009).
Category: