Lillicrap, S C; Owen, B; Williams, J R; Williams, P C (1 October 1990). "Code of Practice for high-energy photon therapy dosimetry based on the NPL absorbed dose calibration service". Physics in Medicine and Biology. 35 (10): 1355–1360. Bibcode:1990PMB....35.1355L. doi:10.1088/0031-9155/35/10/301.
Lillicrap, S C; Owen, B; Williams, J R; Williams, P C (1 October 1990). "Code of Practice for high-energy photon therapy dosimetry based on the NPL absorbed dose calibration service". Physics in Medicine and Biology. 35 (10): 1355–1360. Bibcode:1990PMB....35.1355L. doi:10.1088/0031-9155/35/10/301.