6YEP:
reference: Locked nucleic acid building blocks as versatile tools for advanced G-quadruplex design., Haase L, Weisz K, Nucleic Acids Res. 2020 Sep 5. pii: 5901961. doi: 10.1093/nar/gkaa720. PMID: 32890406

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