2PSP:
reference: Structure of porcine pancreatic spasmolytic polypeptide at 1.95 A resolution., Petersen TN, Henriksen A, Gajhede M, Acta Crystallogr D Biol Crystallogr. 1996 Jul 1;52(Pt 4):730-7. PMID: 15299636

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