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 inflection pressure of SA1 is 10 GPa lower than that of SiO2 glass (Murakami and Bass 2010) and 3 GPa lower than that of MgSiO3 glass (Murakami and Bass 2011).
Category: