DSM5
Read pages 20-23 of the manual under the headlines "Definition of a Mental Disorder" and "Elements of a Diagnosis" (4 minutes)
American Psychiatric Association - 2013
Click https://drive.google.com/file/d/1c0p6yUsyjt5KDIGU-O0KjE0Uv31EZ9ER/view?usp=drive_link link to open resource.