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:Reports of use of other multikinase inhibitors in sarcoma such as imatinib have not been very encouraging [22] or restricted to a smaller patient sub-population such as use of crizotinib in ALK driven tumors [23].
Category: