It's rare that I go out of my way to buy a children's book (being that I have no children and that those I do have contact with are growing up super fast.) But when I saw this book recently, ordering it was a priority.
Written by Seth Kastle, Why Is Dad So Mad? is (as the subtitle clarifies) a book about PTSD and military families. It is simple, straightforward, and very clear, so that even the youngest children of service members with PTSD can understand it. Most importantly, it's written by a retired military veteran with PTSD. He wrote the book to try to explain the changes in him to his young daughters.
Definitely recommend this, and I'm about to add it to Tonia's Big List of Resources for Learning About Disabilities.