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:…et al. 2015), plasma membrane/cell surface (Borisjuk et al. 1998; Lenartowska et al. 2002; Navazio et al. 2002; Šamaj et al. 2008), plasmodesmata (Baluška et al. 1999; Laporte et al. 2003; Bayer et al. 2004; Chen et al. 2005; Lenartowska et al. 2009; Bilska and Sowiński 2010; Christensen et al.…
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