Just went through the schedule to try to compile a list of series going to the Nürburgring Nordschleife, in some variation, and when;
Heusinkveld GT Challenge (GT1/GT2) - Week 1
VRS GT Sprint/Endurance Series - Week 2
GTE Endurance Series (GTE Only) - Week 4 (Weekend ONLY)
Advanced Mazda MX-5 - Week 5
European Sprint Series (LMP1/LMP2/GTE) - Week 7
Fanatec Global Challenge (Caddy/Kia) - Week 8
Radical Racing Challenge - Week 12
Heusinkveld GT Challenge (GT1/GT2) - Week 1
VRS GT Sprint/Endurance Series - Week 2
GTE Endurance Series (GTE Only) - Week 4 (Weekend ONLY)
Advanced Mazda MX-5 - Week 5
European Sprint Series (LMP1/LMP2/GTE) - Week 7
Fanatec Global Challenge (Caddy/Kia) - Week 8
Radical Racing Challenge - Week 12