3CKT:
reference: Two Solutions for the Same Problem: Multiple Binding Modes of Pyrrolidine-Based HIV-1 Protease Inhibitors., Blum A, Bottcher J, Dorr S, Heine A, Klebe G, Diederich WE, J Mol Biol. 2011 Jul 22;410(4):745-55. PMID: 21762812

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