Source list

56 Car Entry For 2020 Total Spa 24 Hours
https://www.dailysportscar.com/2020/10/09/56-car-entry-for-2020-total-spa-24-hours.html

Pre Race Notes: Race Start Delayed, Track Limit Enforcement Returns!
https://www.dailysportscar.com/2020/10/24/pre-race-notes-race-start-delayed-track-limit-enforcement-returns.html

2020 Spa 24 Hours Confirmed Behind Closed Doors
https://www.dailysportscar.com/2020/10/06/2020-spa-24-hours-confirmed-behind-closed-doors.html

2020 24 Hours of Spa
https://en.wikipedia.org/wiki/2020_24_Hours_of_Spa

24h spa history
https://www.crowdstrike24hoursofspa.com/nl/about/history

Total 24 Hours of Spa: a history
https://www.intercontinentalgtchallenge.com/news/1188/total-24-hours-of-spa-a-history

A century of history at the CrowdStrike 24 Hours of Spa
https://www.crowdstrike24hoursofspa.com/news/2718/a-century-of-history-at-the-crowdstrike-24-hours-of-spa

Total 24 Hours of Spa: a history - Part II: 1964-2000
https://www.gt-world-challenge-europe.com/news/1197/total-24-hours-of-spa-a-history-part-ii-1964-2000

European Touring Car Championship
http://touringcarracing.net/Pages/1988%20ETCC.html

24H Spa Track Limit Rules Changed after Driver Criticism
https://sportscar365.com/sro/world-challenge-europe/track-limits-rules-changed-after-driver-criticism/

Track limits defined ahead of 2020 Total 24 Hours of Spa
https://www.gt-world-challenge-europe.com/news/1935/track-limits-defined-ahead-of-2020-total-24-hours-of-spa#:~:text=A%20bulletin%20from%20the%20race,in%20contact%20with%20the%20track.%22