1JSD:
reference: H5 avian and H9 swine influenza virus haemagglutinin structures: possible origin of influenza subtypes., Ha Y, Stevens DJ, Skehel JJ, Wiley DC, EMBO J 2002 Mar 1;21(5):865-75. PMID: 11867515

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