2BRD:
reference: Electron-crystallographic refinement of the structure of bacteriorhodopsin., Grigorieff N, Ceska TA, Downing KH, Baldwin JM, Henderson R, J Mol Biol 1996 Jun 14;259(3):393-421. PMID: 8676377

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