I got this book shortly after Beren came to live with us, and it has been a lifesaver. Terriers tend to be quintessential adolescents all of their lives, and I highly recommend the book. All quotes in my presentation posts come from this book.
Most behavioral problems are alpha problems at their root.
They need a leader, alpha, and when one is not provided in terms they can understand, they will assume that they are alpha. When his mother asserted control, she would stand tall, well up on her toes, and her barks or growls will be low-pitched, deep. You may not feel you need a model of behavior in your life, a mentor, a problem solver, a nourisher. But you are a human adult. You're dog, because he is a dog and because he has been domesticated and lives with another species, will always be like a child.