3CTI:
reference: Relaxation matrix refinement of the solution structure of squash trypsin inhibitor., Nilges M, Habazettl J, Brunger AT, Holak TA, J Mol Biol 1991 Jun 5;219(3):499-510. PMID: 2051485

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