For more on PTSD, you can read the book Posttraumatic Stress Disorder: Scientific and Professional Dimensions by Julian D. Ford. Also, you can have access to the book Diagnostic and Statistical Manual of Mental Disorders (DSM-5®), by American Psychiatric Association and study the PTSD criteria. The International Classification of Diseases and Related Health Problems 10 (ICD-10) classifies PTSD under “Reaction to severe stress, and adjustment disorders.” The ICD-10 criteria for PTSD include re-experiencing, avoidance, and either increased reactivity or inability to recall certain details related to the event. ICD-11 no longer includes verbal thoughts about the traumatic event as a symptom. There is a predicted lower rate of diagnosed PTSD using ICD-11 compared to ICD10 or DSM-5.