2A2T:
reference: Structure of a DNA duplex with all-AT base pairs., Valls N, Richter M, Subirana JA, Acta Crystallogr D Biol Crystallogr. 2005 Dec;61(Pt 12):1587-93. Epub 2005, Nov 19. PMID: 16301792

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