Working on my '00+ stuff I've been watching races on Nascar's YouTube channel.
Back in the day of just getting the internet (2000), photos on sites like nascar.com etc were too small, like 350x. So I got bought a lot of books (behind the scenes) of Nascar for Xmas each year. That was my reference for photos when painting rides in N3, N4, N2k2 etc
Now I'm buying old race programs to find sponsors/logos/contingencies and other photos of hard to find references.
My current oldest Nascar program is Daytona 500 from 1980, not started my early 80's stuff yet.