2XC6:
reference: On the Structure and Dynamics of Duplex GNA., Johnson AT, Schlegel MK, Meggers E, Essen LO, Wiest O, J Org Chem. 2011 Oct 7;76(19):7964-74. Epub 2011 Aug 30. PMID: 21838272

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