Lars Westerlund (Finnish National Archives) has published this booklet available on amazon:
https://www.Finnish SS-Volunteers and Atrocities against Jews, Civilians and Prisoners of War in Ukraine and the Caucasus Region 1941-1943: An Archival Surveyamazon.com/SS-Volunteers-Atrocities-Civilians-Prisoners-1941-1943/dp/9518581002