2JJA:
reference: Duplex structure of a minimal nucleic acid., Schlegel MK, Essen LO, Meggers E, J Am Chem Soc. 2008 Jul 2;130(26):8158-9. Epub 2008 Jun 5. PMID: 18529005

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