| 4XNO: reference: Structural basis for a six nucleotide genetic alphabet., Georgiadis MM, Singh I, Kellett WF, Hoshika S, Benner SA, Richards NG, J Am Chem Soc. 2015 Jun 3;137(21):6947-55. doi: 10.1021/jacs.5b03482. Epub 2015, May 18. PMID: 25961938 |
This OCA 
Structure page
uses Jmol,
developed by the Jmol Development Team
(documentation).