| year of publication | ISBN | author(s) | title |
|---|---|---|---|
| 1998 | 978-0-9531330-0-0 | Hugh Skillen | Enigma Symposium |
| 1999 | 978-0-9531330-1-7 | '' | Enigma Symposium 1999 |
| 2000 | 978-0-9531330-2-4 | '' | Enigma Symposium 2000 |
| 2001 | 978-0-9531330-3-1 | '' | The enigma symposium 2001 |
| 2002 | 978-0-9531330-4-8 | '' | The Enigma Symposium 2002 |
| 2003 | 978-0-9531330-5-5 | Hugh Skillen | The Enigma Symposium 2003 |