Hi Tracy! All the Atkins books are fine but Atkins 72 or the one from the 90s are the ones the doctor himself had a hand in. Newer versions are commissioned by the Atkins company and push the bars and frankenfoods which Atkins would never have allowed - if you ignore that part though, except for being a bit more lax on certain vegetables, the actual diet advice is mostly the same.
India knights pig to twig book is a funny and easy read version of the same diet principles.
Whichever Atkins book you get, ignore any advice on subtracting fibre from your carb counts - its already done for us over here but they never anglicized this part of the book.