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:Although we found manual dissection of BG01 was successful, we adapted this line to trypsin-passaging on feeders and on Matrigel to facilitate comparison with an independently-derived line, HUES-7 (Cowan et al., 2004).
Category: