3ALX:
reference: Structure of the measles virus hemagglutinin bound to its cellular receptor SLAM., Hashiguchi T, Ose T, Kubota M, Maita N, Kamishikiryo J, Maenaka K, Yanagi Y, Nat Struct Mol Biol. 2011 Feb;18(2):135-41. Epub 2011 Jan 9. PMID: 21217702

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