R&R https://worldradiohistory.com/Archive-All-Music/Radio_and_Records.htm (more on radio than Billboard by far)If I remember correctly, beeing a foreigner from the other side of the planet, most stations close to the Top 40 format in LA kinda panicked and drop DJs to go more sweepers/music. I dont have the copies no more but i believe that both "Billboard" and "Music & Media" discussed this a few times. They shivered that the "Worst to first from NYC" came to LA. And after some time it normalized it self again.
Billboard: https://worldradiohistory.com/Archive-All-Music/Billboard-Magazine.htm
Music & Media (which did not cover the US directly) https://worldradiohistory.com/Music-and-Media.htm
And now you have thousands of complete issues of those magazines.But I might be wrong in my memory, we did'nt have internet back then,