Notes:
Ulrich Graf crashed after his Kreidler suffered a rear tyre failure while travelling at a speed of about 130 km/h, on the fifth lap of the 50 cm³ Grand Prix of Yugoslavia. He was sent into the rocks skirting the track and died shortly afterwards in a local hospital.

Ulrich Graf had started racing in 1968; he had achivied three national championships (1969, 1972 and 1973) and a third place in the 50 cm³ World Championship in 1976. He had won the Yugoslavian Grand Prix the year before his death.

Yugoslavian promoters had received an ultimatum from the International Federation before the race, if they did not improve the safety of the street track the Grand Prix of Yougoslavia would not be held in the circuit of Opatija anymore. The race, which ended in a complete disaster with Urich Graf and the Italian Giovanni Ziggiotto killed and nineteen other riders injuried, was eventually the last held there and the World Championship moved to the circuit of Rijeka.

• Magazine Motosprint, Italy, issue 24/1997.
• Newspaper Corriere della Sera, Milan, Italy, issue of 20 June 1977, article "Non si correrà più ad Abbazia ma le rocce hanno ucciso ancora" by Giancarlo Falletti.
• Website Racing Memory, by Vincent Glon, page http://www.chez.com/racingmemo/MOTORSPORT/MOTO-GP-1977.htm .
• Website Der Schweizer Motorradrennsport und seine Histoire, page http://www.eggersdorfer.info/schweiz_geschichte/schweizer-rennsportgeschichte8.html .
• Website Racing Circuits, by Daniel King, page http://www.the-fastlane.co.uk/racingcircuits/Croatia/Opatija.html .
• Website MotoGp, page https://www.motogp.com/it/riders/profile/Ulrich+Graf
• Website Website Motorsportstatistik, page http://www.motorsportstatistik.com/Gone/gone_but_not_forgotten_de.html
• E-mail by Chris Hall, dated 04 May 2004.
• E-mail by Andy Marlow, dated 24 December 2004.
• E-mail by Andy Marlow, dated 02 January 2005.