5UK1:
reference: CryoEM Structure of an Influenza Virus Receptor-Binding Site Antibody-Antigen Interface., Liu Y, Pan J, Jenni S, Raymond DD, Caradonna T, Do KT, Schmidt AG, Harrison SC, Grigorieff N, J Mol Biol. 2017 Jun 16;429(12):1829-1839. doi: 10.1016/j.jmb.2017.05.011. Epub, 2017 May 12. PMID: 28506635

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