2HNS:
reference: Structure of an AAGU Tetraloop and its Contribution to Substrate Selection by yeast RNase III., Gaudin C, Ghazal G, Yoshizawa S, Elela SA, Fourmy D, J Mol Biol. 2006 Oct 20;363(2):322-31. Epub 2006 Aug 16. PMID: 16979185

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