1T4U:
reference: Oxyguanidines. Part 2: Discovery of a novel orally active thrombin inhibitor through structure-based drug design and parallel synthesis., Lu T, Markotan T, Coppo F, Tomczuk B, Crysler C, Eisennagel S, Spurlino J, Gremminger L, Soll RM, Giardino EC, Bone R, Bioorg Med Chem Lett 2004 Jul 16;14(14):3727-31. PMID: 15203151

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