1. Aragón Aragón , M. J. Castelli , A. Chalkley , M. J. Gaughan , J. M. 2016 Hospital productivity growth in the English NHS 2008/09 to 2013/14 CHE Research Paper 138 https://www.york.ac.uk/media/che/documents/papers/researchpapers/CHERP138_Hospital_Productivity_NHS.pdf
2. Hospital trusts productivity in the English NHS: Uncovering possible drivers of productivity variations;Aragón Aragón;PLOS ONE,2017
3. Bojke , C. Castelli , A. Goudie , R. Street , A. Ward , P. 2012 Productivity of the English National Health Service 2003-4 to 2009-10 CHE Research Paper 76 http://www.york.ac.uk/media/che/documents/papers/researchpapers/CHERP76_Productivity_of_the_English_NHS.pdf
4. Bojke , C. Castelli , A. Grašič , K. Howdon , D. Street , A. D. 2016 Productivity of the English NHS: 2013/14 update CHE Research Paper 126 http://www.york.ac.uk/media/che/documents/papers/researchpapers/CHERP126_NHS_productivity_update2013_14.pdf