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:However, they are very unstable in all other situations, namely, in simulations of GQs lacking the channel ions (54,60), in G-triplexes even in excess salt conditions (61) and in isolation (the present work).
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