Cohen, David; Edelsack, Edgar A.; Zimmerman, James E. (1970). "Magnetocardiograms taken inside a shielded room with a superconducting point contact magnetometer". Applied Physics Letters. 16 (7). AIP Publishing: 278–280. Bibcode:1970ApPhL..16..278C. doi:10.1063/1.1653195. ISSN 0003-6951. /wiki/Bibcode_(identifier)