Primary human structure record 4HHB, PDB DOI doi.org/10.2210/pdb4HHB/pdb . Related byline G. Fermi, M. F. Perutz, B. Shaanan and R. Fourme, Journal of Molecular Biology 175, 159–174 (1984), DOI doi.org/10.1016/0022-2836(84)90472-8 , PMID 6726807. Macromolecules and assembly identify two alpha and two beta chains. Primary abstract: 1.74 angstrom refinement using room-temperature synchrotron X-ray film data. Literal publication initials retained; Perutz Work tag uses the verified canonical person name.
Primary Abstract, pubmed.ncbi.nlm.nih.gov/6726807/ : independence of the reported local geometry from imposed restraints was tested by unrestrained refinement of the entire molecule, starting from modified haem geometry. This is the specific model-sensitivity test cited in the G. Fermi profile.