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:Titan and typical C. neoformans cells have different cell wall composition
In vivo C. neoformans cells vary in size, from cells less than 3 μm in cell body diameter to cells more than 100 μm in diameter (Feldmesser et al., 2001; Okagaki et al., 2010; Zaragoza et al., 2010; Alanio et al., 2015).
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