Collecting these documents was like trying to make a jigsaw puzzle from which many pieces are missing, the difference being that in this case one often does not even know that something is missing. However, the lack of other pieces is known. [47] As regards my own country (the Netherlands), I am fairly sure that the collection of documents is well-nigh complete. Some statements issued by Churches were published in Bulgarian or Slovak, etc., but not in English. Even such documents as were available in English were not generally known. Most of the material in this book had to be translated from Hebrew, French, German, Dutch, Norwegian, Swedish, Danish, Slovak, Hungarian, Bulgarian or Greek. Initially, I sent a circular letter to the heads of Churches in Eastern Europe asking for information and I received some replies, though not many. Some replies stated that no documents were available because everything had been destroyed during the war. This seems quite possible, and perhaps we must give the Churches in question the benefit of the doubt. Moreover, it was not advisable, for security reasons, to keep certain documents. Thus, for instance, all documents of the World Council of Churches and its preceding organizations, which might incriminate Christian leaders in Germany, were destroyed when, in 1940, it was feared that Germany would invade Switzerland. [48] <3> Yet, some Churches, which probably could have sent material, and which in some cases as, for example, the Churches in Bulgaria and Greece, had a good record of resistance against anti-Semitism, failed to do so. It would appear that Church archives are sometimes the safest place in the world for documents not to be found. The Library and Archives of "Yad Vashem", in Jerusalem, had much material. I was also able to spend some days in the Wiener Library, in London, and in the Library of the World Council of Churches, at Geneva. I could never have succeeded in finding the material and having it translated without the help of many interested friends, Jews as well as Christians, to whom I am deeply indebted. It would be difficult to mention all their names, but I should like at least to express here my indebtedness to the late Director of "Yad Vashem", Dr. Arjeh Leon Kubovy, of blessed memory; and to Dr. Shaul Esh, of blessed memory, who made valuable suggestions for the chapters on Germany. I am also especially indebted to Dr. J. Robinson, of New York, and Prof. Dr. C. Augustijn, of Amsterdam, who read the manuscript and suggested many improvements. Of course the responsibility for any eventual mistakes solely rests on me. I am deeply grateful for all the kind help rendered to me by the Chief Librarian of "Yad Vashem", Miss Ora Alcalay, and her assistants.