I own a 30+ year old hardback copy of Richard Foster's Celebration of Discipline book. I know he's updated the book a few times so I decided to search Logos to add it to my library and read the updated version.
To my joy, I found that Logos has the Audio book for 20 th Anniversary Celebration of Discipline. To my shock, I also discovered that Logos does NOT have either the original nor the 20th anniversary edition of the book.
I find that extremely strange, if not bizarre.