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 potential for LMTM to be active at the low dose of 4 mg twice a day and the lack of doseresponse was unexpected given the results of an earlier Phase II placebo-controlled study using the oxidized form of the methylthioninium (MT) moiety as methylthioninium chloride (MTC) [13].
Category: