2JXS:
reference: Bulged adenosine influence on the RNA duplex conformation in solution., Popenda L, Adamiak RW, Gdaniec Z, Biochemistry. 2008 May 6;47(18):5059-67. Epub 2008 Apr 10. PMID: 18399645

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