I would start off with Piper and then read Metta and debrosse. Piper gives a wider overview and sort of answers most of the questions one might have while Debrosse and Metta go into the finer detail. One doesn't have to agree with everything they write to understand the plot and who was ultimately involved.

For instance, Metta makes connetions between Mossad and Nazis where they only really exist on past indirect relations. Schacht, for instance, Hitler's original banker and some banks that financed Hitler, which now front Mossad and Israel causes who played a hand in the rise of Nazism in the 20's, were not Nazis per say but were funding the cause indirectly for Zionist and profit reasons. Schacht was a freemason and in 1940 was fired by Hitler for being an agent of British high finance. Once Hitler liquidated all Freemasonry, according to German documents, Schacht became obstructionist and looked to use his conncetions to destroy nazi Germany. He was thrown in Dachu but survived. Schacht wrote a book called the Magic of Money where he claims to be the creator of the Haavara agreement which sought to transfer german Jews to Palestine which was not the first choice of Nazis. He writes that Hitler stopped the transfer agreement in 1938 and that he did not why. Schacht also says that he hated Gottfried Feder for attack on interest and high finance. That Feder was destructive and would destroy the goodwill of bankers. While Hitler did hire Schacht and left Feder to a low-tier government role in 1933, when he thought he's be of higher use, which he later left to teach; at wars time, when Schacht was fired and thrown in Dachu, Feder's pupil, who he taught, Walther Funk, was placed in Schacht's position.

I'm only trying to make the case that the Prussian Masonic and Mossad relationships with the Nazis were indirect and eventually hostile and had little to do with the assassination of JFK after the war. Mussoliniyist agents, however, were part of the assassination of JFK literally because they thought JFK wasn't useful enough in combating communism and because he wanted entente and a CIA which was fronted by war veterans like Smith who were agaisnt unconventional warfare rather than unconventional warfare Zionists and Masonic agents, hence, JFK had to go for that reason alone among many others, such as his stance agaisnt Nuclear Israel and Zionism in general.

Think of the revisionist Zionist Jew Jabotinsky, who fought for Mussolini on the Ethiopian front and conducted drills with the Italian army. Jabotinsky had no problems with Mussolini but believed Hitler was the enemy of Zionism and the establishement of Israel which is clearly observed when we take into account Operation Atlas and various other campaigns where the Nazis fought along side the Arabs in palestine and armed them.

So, the obstructionist elements in the Nazi regime did have a relationship with Mossad and high finance. Which leads me to believe that there were certainly more Zionists (many being Ashkenazi Jews) working for the Nazis, direct or indirect, probably in many cases as double agents and obstructionsits, than what is believed.