Anyone who knows what anxiety, and sometimes anguish, parents go through when they have a child who is still not talking at age two, three or even four, can appreciate what a blessing it can be to have someone who can tell them what to do — and what not to do. That someone is Professor Stephen Camarata of the Vanderbilt University Medical Center, whose recently published book, "Late-Talking Children" gives parents information and advice that they are not likely to find anywhere else. And it does so in plain English. Professor Camarata has been researching, diagnosing and treating children...