4C2M: Structure Of Rna Polymerase I At 2.8 A Resolution
reference: RNA polymerase I structure and transcription regulation., Engel C, Sainsbury S, Cheung AC, Kostrewa D, Cramer P, Nature. 2013 Oct 31;502(7473):650-5. doi: 10.1038/nature12712. Epub 2013 Oct 23. PMID: 24153182

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