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:The main specifications we shall deal with here are (Landau et al., 1995b):
• stability of the loop [C G0] • a maximum value of less than 6 dB for the sensitivity function T22(G0, C) =
1/(1 + G0C).
Category: