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:For nocodazole treatment of embryos, L4 worms were grown on perm-1(RNAi) feeding plates at 20¬∞C for 16-18 hr, then dissected in an open imaging chamber filled with osmotic support medium (Carvalho et al., 2011;
 Wueseke et al., 2016) and 20 ¬µg/ml nocodazole (Sigma).
Category: