Question: The Deutsche Gesellschaft für Schädlingsbekämpfung mbH (translation: German Corporation for Pest control), in short Degesch, is a German chemical corporation, Degesch had the patent of the infamous Zyklon B, was the trade name of a cyanide-based pesticide invented in which country in the early 1920s?

Context paragraphs:
Tesch &amp; Stabenow: The corporation Tesch & Stabenow (in short Testa) was a market leader in pest control chemicals between 1924 and 1945 in Germany east of the Elbe.  Testa distributed Zyklon B, a pesticide consisting of inert adsorbents saturated with hydrogen cyanide, a volatile liquid extremely toxic to animals and humans.  For legitimate use as a pesticide, Zyklon B included a warning odorant as not everyone can smell cyanide or recognize its faint almond-like odor.  The company sold Zyklon B to the Wehrmacht and the SS in Auschwitz-Birkenau without the odorant, clearly showing that it was intended for use on humans.  Two directors of Testa were convicted and executed for assisting in the mass murder of Jews during the Second World War.  The company continued after the war and merged with Heerdt-Lingler GmbH (HeLi) in 1979.

Deutsches Archiv für Erforschung des Mittelalters: The Deutsches Archiv für Erforschung des Mittelalters ("German Archive for Research into the Middle Ages"; often shortened to Deutsches Archiv or DA) is a historical journal on history between 400 CE and 1500 CE, published by the Monumenta Germaniae Historica (MGH), the German institute for study of the Middle Ages.  It numbers its volumes from 1937, named the "Deutsches Archiv für Geschichte des Mittelalters" ("German Archive for Medieval History") from volume 7 (1944).  Its forerunners were the twelve-volume 1820-1874 "Archiv der Gesellschaft für ältere deutsche Geschichtskunde" ("Archive for study of earlier German history") and the fifty-volume 1876-1935 "Neue Archiv der Gesellschaft für ältere deutsche Geschichtskunde" ("New Archive for the study of earlier German history" or "NA").  It has been published in Weimar then Cologne by Böhlau Verlag, its current publisher, and is the oldest German-language journal on medieval history.

Deutsche Gesellschaft für Luft- und Raumfahrt: German Society for Aeronautics and Astronautics (DGLR; German: "Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V." ) is a German aerospace society.  It was founded in 1912 under the name of "Wissenschaftliche Gesellschaft für Flugtechnik" (WGF).  It is the second oldest technical and scientific society in aerospace in the world.

Bruno Tesch: Bruno Emil Tesch (14 August 1890 – 16 May 1946) was a German chemist and entrepreneur.  Together with Gerhard Peters and Walter Heerdt, he invented the insecticide Zyklon B, infamous for having been used by Nazi Germany to exterminate approximately a million of the victims of the Holocaust.  He was the owner of Tesch & Stabenow (called "Testa"), a pest control company he co-founded in 1924 with Paul Stabenow in Hamburg, Germany, which was a major supplier of Zyklon B to the Nazi concentration camps.

Deutsche Medizinische Wochenschrift: The Deutsche Medizinische Wochenschrift ("German Medical Weekly") (DMW) is a German medical journal established in 1875 by Paul Börner.  In the 1980s it was ranked 10th in the world in terms of its impact factor, but in the succeeding two decades the journal lost much of its preeminence due largely to the declining importance of the German language in medical publications and the appearance of a large number of new medical journals in the English language.  It is currently published by Georg Thieme Verlag and is an official publication of the Deutsche Gesellschaft für Innere Medizin and the Gesellschaft Deutscher Naturforscher und Ärzte.  The editor in chief is Martin Middeke.  According to the Journal Citation Reports, its 2008 impact factor is 0.625, ranking it 86 out of 107 in the category "General and Internal Medicine".

Degesch: The Deutsche Gesellschaft für Schädlingsbekämpfung mbH (translation: German Corporation for Pest control), in short Degesch, is a German chemical corporation.  Degesch produces pesticides used against weeds and insects.  Degesch had the patent of the infamous Zyklon B, a pesticide that was used to execute people in gas chambers of German extermination camps during the Holocaust.  Through the firms Tesch & Stabenow GmbH (Testa) and Heerdt-Linger (Heli) Degesch sold the poisonous gas Zyklon B to the German Army and the Schutzstaffel, abbreviation SS.

Zyklon B: Zyklon B ( ; ] ; translated Cyclone B) was the trade name of a cyanide-based pesticide invented in Germany in the early 1920s.  It consisted of hydrogen cyanide (prussic acid), as well as a cautionary eye irritant and one of several adsorbents such as diatomaceous earth.  The product is infamous for its use by Nazi Germany during the Holocaust to murder approximately one million people in gas chambers installed at Auschwitz-Birkenau, Majdanek, and other extermination camps.

DGMK: Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e.V. (DGMK, in English: DGMK German Society for Petroleum and Coal Science and Technology) is a German national association of academics and professionals in the petroleum industry.  It is based in Hamburg, Germany and the current chairman is Wilhelm Keim.  The name DGMK derives from the former association name of Deutsche Gesellschaft für Mineralölwissenschaft und Kohlechemie (German Society of Mineralogy and Coal Chemistry).

Gerstein Report: The Gerstein Report was written in 1945 by Kurt Gerstein, an Obersturmführer (First Lieutenant) of the Waffen-SS who rose to become the Head of Technical Disinfection Services of the SS, and in that capacity supplied hydrogen cyanide (Zyklon B) from Degesch ("Deutsche Gesellschaft für Schädlingsbekämpfung") to Rudolf Höss in Auschwitz and conducted the negotiations with the owners.  On 17 August 1942, together with Rolf Günther and Wilhelm Pfannenstiel, Gerstein witnessed the gassing of some 3,000 Jews in the extermination camp of Belzec in occupied Poland.  The report features his eyewitness testimony.  It was used as evidence in the Nuremberg Trials.

Gesellschaft für Nuklear-Service: The Gesellschaft für Nuklear-Service mbH (GNS) carries out services in the field of radioactive waste disposal and decommissioning of nuclear facilities and operates through several subsidiaries interim storage depots for spent fuel and radioactive waste as in Gorleben and Ahaus.  It was created in 1977 after the Gesellschaft für Nuklear-transporte mbH (GNT) was founded in 1974.

Supporting paragraphs: Degesch Zyklon B
Answer: Germany