I’ve just finished writing my first book. I won’t reveal too much, but the book is on marketing, copywriting and consumer psychology. To better illuminate some psychological principles early in the book, I have decided to include an appendix on segmenting constituents based on their personality traits in order to better deliver marketing messages that resonate with their ways of thinking and their buying habits. The appendix in question is essentially a summary of ideas from the book “You are What You Choose” by Scott De Marchi and James T. Hamilton. Now, I have given full credit to the authors, and I was very careful to make it very clear that these ideas are theirs and not mine. In addition I put their ideas into my own words so as not to infringe their copyright. Based on what I know about plagiarism and copyright laws I should be safe. Am I correct in making that assumption? The other issue is the fact that I feel as though I have revealed the essence of their ideas, the actual gold that makes their book so valuable to marketers – although there are many subtleties to their ideas that I did not mention. Is this legal? Suppose they weren't happy about this? Would they have a legal case against me?