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:In addition, PTH-induced release of calcium from bone is substantially impaired in the presence of hypomagnesaemia, as magnesium depletion interferes with the generation of cAMP in response to PTH [2, 3].
Category: