Malcolm-It seems to me that the X prefix can come from English Columbia- the P could mean personal- many English mx numbers start with WAX for the electricals. are they acoustical?-Mickey -----Original Message----- From: Malcolm Sent: Saturday, November 09, 2019 10:02 AM To: [log in to unmask] Subject: [ARSCLIST] Heart murmur record set A while back I bought a seven record 12", single sided, Columbia 78 set entitled "Stethoscopic Heart Records", Co M-600, which I mean to give to a cardiologist friend for Christmas. I have not been able to come up with any discographic info on it and the liner notes do not quote recording dates, a release date, recording location(s) or even a price for the set. The matrix numbers are XP 29125, XP 29126, XP 29520, XP 29908, XP 29909, XP 29978 and XP 30060. Help will be gratefully accepted from those who delves into this sort of esoterica. It's outside my normal lines of inquiry. Thanks, Malcolm Rockwell