In 1990, a valiant attempt was made to focus the attention of one of the camps, Mauthausen in Austria, on its impact on Roma, Gypsies. See Austria Road Ways; and https://www.nytimes.com/1990/08/07/world/mauthausen-journal-at-a-death-camp-gypsies-confront-indifference.html. The camp is largely intact, buildings, functions, the quarry for forced labor and related killings, inside is a display including:
There is extensive non-English research: for example, click on the translation for the search we entered, for "Ausrottung der Zigeuner")(this site is not secure) http://www.sintiundroma.de/sinti-roma/ns-voelkermord/vernichtung.html. The documentation center in Nuremburg has more: http://www.sintiundroma.de/start.html. Move down the list of countries, areas with documentation of the extermination.
Our nominal Car-Dan Tour Company (just Dan and me) have visited camps including Buchenwald, Bergen-Belsen. See Germany Road Ways; and Auschwitz, see Poland Road Ways.