Ringdal, K. G., Skaga, N. O., Steen, P. A., Hestnes, M., Laake, P., Jones, J. M., & Lossius, H. M. (2012). Classification of comorbidity in trauma: Agreement and reliability of the pre-injury ASA-PS Scale. BioMed Central.

Ringdal, Kjetil G., Nils Oddvar Skaga, Petter Andreas Steen, Morten Hestnes, Petter Laake, J Mary Jones, e Hans Morten Lossius. Classification of Comorbidity in Trauma: Agreement and Reliability of the Pre-injury ASA-PS Scale. BioMed Central, 2012.

Ringdal, Kjetil G., et al. Classification of Comorbidity in Trauma: Agreement and Reliability of the Pre-injury ASA-PS Scale. BioMed Central, 2012.