Euronymous's Epistles

Yah. Euronymous's is correct. Leaving the "s" off is a common mistake. It's as annoying to me as inappropriate/incorrect apostrophes ie 09', CD's, etc
 
Ha, yeah, that reminds me of: when I went to see Cynic (and Dragonforce hahahahahahaha) I was leaving the venue and happened to notice a Kid Rock poster on the wall. He dated it 99'.