Mayo Clinic – Not only are they known for being “the place” they also have a very useful list of diagnoses and disorders. If you have a question about a medical diagnoses beyond what I cover in the book, they are an excellent resource.
National Child Traumatic Stress Network – If your child has been exposed to a traumatic event and has Post Traumatic Stress Disorder, this site has a lot of excellent information, particularly about the basics of trauma, ways it is treated, and what you can do.
National Association for the Dually Diagnosed – The NADD is an association for treatment of people with Developmental Delays (most commonly Autism and Intellectual Disability) who also have another mental health diagnosis. Their site is primarily written for professionals, but may be useful for parents, especially the information page.