Here is a South Park doujinshi which features alot of characters! Scanned by me (Adorable Doujinshi Scanlations) https://adorable-scanlations.blogspot.com/
scan #357
direct download link -https://www.mediafire.com/file/g76ljvyqp9mvna9/%2528HIP%25EF%25BC%258ALOCCO%2529_Colorado_Ensemble.zip/file