http://www.southstaffordshirepct.nhs.uk/policies/clinical/Clin55_DiagnosticUltrasoundProcedures.pdf . Approved 27 Apr 2009. http://www.essr.org/html/img/pool/shoulder.pdf ; http://www.essr.org/html/img/pool/elbow.pdf ; http://radiology.rsna.org/content/252/1/157.full.pdf ....