4C7L:
reference: The murine coronavirus hemagglutinin-esterase receptor-binding site: a major shift in ligand specificity through modest changes in architecture., Langereis MA, Zeng Q, Heesters BA, Huizinga EG, de Groot RJ, PLoS Pathog. 2012 Jan;8(1):e1002492. doi: 10.1371/journal.ppat.1002492. Epub 2012, Jan 26. PMID: 22291594

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