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:If larval release occurred before the end of the monitoring period, monitoring was ceased, as Forward et al. (2003, 2005) found that female blue crabs become arrhythmic following larval release unless re-entrained to the tidal cycle.
Category: