"The Way of the Cat" by Pamela Merritt. It's available free with a Kindle subscription on Amazon. According to this author, there are three types of cat personalities, with of course some blending in many cases. I have discovered that Sheena and Zoey are Gamma types, meaning that they will always be shy and cautious, unfortunately that is something they will never grow out of. Avalon, my departed kitty, was definitely an Alpha. Since I am once more on the quest for a third cat, this book will help my selection process enormously, since she gives advice on combining the different personalities together. According to her, an Alpha cat may cause trouble with two shy Gammas, but a Beta may be more easy going. Great reading!