205D:
reference: Structure of an RNA double helix including uracil-uracil base pairs in an internal loop., Baeyens KJ, De Bondt HL, Holbrook SR, Nat Struct Biol 1995 Jan;2(1):56-62. PMID: 7719854

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