Notes:
Three fatalities occurred in each of the first three editions of the "500 Km" of Vallelunga - Trofeo Gino Magnani, motorcycle production race held in 1971, 1972 and 1973.

First occurred the accident of Alex Spiaggia who was killed during practice, on 24 October 1971. During the first lap of the 2nd edition of the race, held on 22 October 1972, Maurizio Cecere crashed almost at the same spot as Alex Spiaggia's motorcycle had.

One year later, at approximately 15h30 on Sunday, 21 October 1973, the Italian rider Gaetano Bonali, 31 year-old from Pavia, lost control of his Laverda 750 on the approach to the Trincea bend, while traveling at 150 km/h at the exit of the chicane. Bonali was thrown into air when his machine hit the straw bales, landing head-on on the asphalt 20 meters ahead.

Gaetano Bonali was reached by the rescue team's ambulance in a matter of minutes, and immediately taken to San Filippo Neri hospital in Rome. Sadly, he succumbed to his cranial and pelvis fractures and internal injuries eight days later, without regaining consciousness.

According to eyewitnesses report, Gaetano Bonali's motorbike went out of control when the rider turned his head to look back at other competitors. Tommaso Piccirilli-Felice Pietrinferni on a Honda 750, eventually were the winners of the race which was not stopped after the accident.

• Newspaper "Stampasera" (Turin, Italy) issue of Monday, 22 October 1973, page 18, article "E' morente il pilota Bonali caduto in pista a Vallelunga", retrieved by website http://www.archiviolastampa.it/ .
• Newspaper "La Stampa" (Turin, Italy) issue of Tuesday, 23 October 1973, page 19, article "Gaetano Bonali sempre gravissimo. Adesso basta con le corse brivido", retrieved by website http://www.archiviolastampa.it/ .
• Newspaper "El Mundo Deportivo" (Barcelona, Spain), issue of Wednesday, 24 October 1973, article "Grave accidente en Vallelunga", page 20, retrieved by website http://www.elmundodeportivo.es/hemeroteca/index.html .
• Newspaper "La Stampa" (Turin, Italy) issue of Tuesday, 30 October 1973, page 19, article "Dopo otto giorni è morto Bonali", retrieved by website http://www.archiviolastampa.it/ .
• Newspaper "La Stampa" (Turin, Italy) issue of Thursday, 01 November 1973, page 19, article "Motociclismo senza futuro", retrieved by website http://www.archiviolastampa.it/ .
• Website Motor Racing Circuits, by Daniel King, page http://www.the-fastlane.co.uk/racingcircuits/Italy/VallelungaMotorcycle.html .