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:It is likely that during lactation
a variety of physiological responses to stress are suppressed, including responsiveness of the adrenocortical axis; hyporesponsiveness during lactation has been described for rats Rattus norvegicus (e.g. Windle et al. 1997) and humans (Altemus et al. 1995).
Category: