tell me the name of the lab tests that patient 42956 last received until 09/2105?
select d_labitems.label from d_labitems where d_labitems.itemid in ( select labevents.itemid from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 42956 ) and strftime('%y-%m',labevents.charttime) <= '2105-09' order by labevents.charttime desc limit 1 )