Ghebremedhin E, Del Tredici K, Langston JW, Braak H. Diminished tyrosine hydroxylase immunoreactivity in the cardiac conduction system and myocardium in Parkinson's disease: an anatomical study. Acta Neuropathol. 2009 Dec;118(6):777–84. doi: 10.1007/s00401-009-0596-y. PMID: 19802627.