6M0C:
reference: High-Resolution Structures of DNA Minidumbbells Comprising Type II Tetraloops with a Purine Minor Groove Residue., Ngai CK, Lam SL, Lee HK, Guo P, J Phys Chem B. 2020 Jun 15. doi: 10.1021/acs.jpcb.0c03163. PMID: 32484672

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