4ZCJ:
reference: Design and Structure of an Engineered Disulfide-Stabilized Influenza Hemagglutinin Trimer., Lee PS, Zhu X, Yu W, Wilson IA, J Virol. 2015 Apr 29. pii: JVI.00808-15. PMID: 25926650

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