1. Baule, G. M., and McFee, R., 1963, Detection of the magnetic field of the heart, Am. Heart J., 66: 95.
2. Berthel, K. H., Albrecht, G., Kirsch, G., Nowak, H., Vodel, W., and Zach, H. G., 1986, Application of dc-SQUIDs for biomagnetic measurements, in: “Proc. 4th Czechoslovakian. Symp. on Weak Superconductivity, Smolenice: 53.
3. Cohen, D., 1970, Large-volume conventional magnetic shields, Rev. de Phys. Appl., 5: 53.
4. Cohen, D., Edelsack, E., and Zimmerman, J. E., 1970, Magnetocardiograms taken inside a shielded room with a superconducting point-contact magnetometer, Appl. Phys. Lett., 16: 278.
5. Kelhae, V. O., 1981, Construction and performance of the Otaniemi magnetically shielded room, in: “Biomagnetism”, S. E. Erne, H. D. Hahlbohm and H. Leubbig, eds., Walter de Gruyter, Berlin: 33.