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:This rhythm is present in ovigerous blue crabs during all stages of egg development, in many crabs between clutches of eggs and continues as crabs cycle through successive clutches (Hench et al. 2004; Forward et al. 2005).
Category: