2OMG: Structure Of Human Insulin Cocrystallized With Protamine And
reference: Structural characterization of insulin NPH formulations., Norrman M, Hubalek F, Schluckebier G, Eur J Pharm Sci. 2007 Apr;30(5):414-23. Epub 2007 Jan 20. PMID: 17339105

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).