Worm, Esben S., et al. “Inter- and Intrafractional Localisation Errors in Cone-Beam CT Guided Stereotactic Radiation Therapy of Tumours in the Liver and Lung”. Acta Oncologica, vol. 49, no. 7, Oct. 2010, pp. 1177-83, doi:10.3109/0284186X.2010.498435.