CRS Reports (Congressional Research Service) are produced by the public policy research arm of Congress and are heavily researched and written by experts in the field on legislative issues. CRS Reports are available fulltext from 1916 to the present. The reports are great for background information and introduction to the issues. The reports are found in the Congressional Publications database.
Not every national group or movement will be covered, but do check.
For example, there is at least one report for these groups (I didn't search all of the groups on your list)
"Black Panthers"
"Irish Republican Army"
"Kurdish Workers' Party" or PKK
"Ku Klux Klan"
Using the search: "Kurdish Workers' Party" or PKK
Results
Document