"Drawn ... [from] largely unexplored and unpublised material in particular the records of the Reichsministerium für Bewaffnung und Munition and those ...
"Drawn ... [from] largely unexplored and unpublised material in particular the records of the Reichsministerium für Bewaffnung und Munition and those of the Wirtschafts- und Rüstungsamt of Oberkommando der Wehrmacht" now in the archives of the Air Historical Branch of the British Air Ministry.