The original version of this book was published in 1933 under the title De geldbronnen van het nationaal-socialisme, 3 gesprekken met Hitler (Financial origins of national socialism) in the Netherlands. According to Jean Gustave Schoup (sometimes spelled as Jan Gustaaf Schoup) the original text had been provided by Sydney Warburg and J.G. Schoup had translated this text English into Dutch. After the book came out the Dutch publisher learned from various sources that no “Sydney Warburg” existed in the New York Warburg family and called back all copies from book dealers and destroyed the whole edition.[1]

One of the three surviving copies found its way to England, was translated into English and deposited in the British Museum. This copy and the translation were later withdrawn from circulation and are presently “unavailable” for research. The second Dutch language copy was acquired by Chancellor Schussnigg of Austria. Nothing is known of its present whereabouts. The third Dutch survivor found its way to Switzerland and was translated into German in 1947.

The original Dutch text was republished in 2008 together with an introduction by Karl Hammer Kaatee

The book that has been published under the pseudonym Sydney Warburg, De Geldbronnen van het nationaal Socialisme: drie gesprekken met Hitler (Funding of National Socialism: Three Conversations with Hitler), published by Van Holkema & Warendorf’s Uitg.-Mij. NV disappeared almost immediately from bookstores. This book dealt with funding received by the Nazi Party in 1929, 1931 and 1933.
[archiveorg HitlersSecretBackersSydneyWarburg198395pgsPOL.sml_201903 width=560 height=384 frameborder=0 webkitallowfullscreen=true mozallowfullscreen=true]
https://archive.org/download/HitlersSecretBackersSydneyWarburg198395pgsPOL.sml_201903/Hitlers_Secret_Backers-Sydney_Warburg-1983-95pgs-POL.sml.pdf