1QSK:
reference: Solution structure of a five-adenine bulge loop within a DNA duplex., Dornberger U, Hillisch A, Gollmick FA, Fritzsche H, Diekmann S, Biochemistry 1999 Sep 28;38(39):12860-8. PMID: 10504256

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