3CXK:
reference: The plug-based nanovolume Microcapillary Protein Crystallization System (MPCS)., Gerdts CJ, Elliott M, Lovell S, Mixon MB, Napuli AJ, Staker BL, Nollert P, Stewart L, Acta Crystallogr D Biol Crystallogr. 2008 Nov;64(Pt 11):1116-22. Epub 2008, Oct 18. PMID: 19020349

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