Litterature
- Dalsgaard-Nielsen T. Studies On Intracranial Vascular Sounds. Acta Psychiatrica et Neurologica 1939; 14: 69–87
- Engström H., Graf W. On Objective Tinnitus and Its Recording. Transactions of the XI Northern oto-laryngological Congress. Acta Oto-laryngologica 1950; 127–137, Supplementum XCV
- Engström H., Graf W. Recording of Objective Tinnitus. Acta Oto-laryngologica. 1952; XLI: 228–234
- Graf W. Nordisk Medicin. 1945; 28: 2499