^The Oracles of the Ancient World: A Comprehensive Guide (Duckworth Archaeology) by Trevor Curnow,2004,page 184,"... outside it, to the N, there is a place called Aornum, with a sacred cave called the Charonium which emitted deadly vapours...""
^The Greek Myths (Volume 1) by Robert Graves, 1990),page 112: "... He used the passage which opens at Aornum in Thesprotis and, on his arrival, not only charmed the ferryman Charon..."
^Pausanias, Description of Greece,Boeotia9.30.1, Others have said that his wife died before him, and that for her sake he came to Aornum in Thesprotis, where of old was an oracle of the dead. He thought, they say, that the soul of Eurydice followed him, but turning round he lost her. The Thracians say that such nightingales as nest on the grave of Orpheus sing more sweetly and louder than others.