User blog comment:El Alamein/Manfred von Richthofen vs. Claus von Stauffenberg/@comment-4978251-20140521014101/@comment-4978251-20140521104907

It was mentioned here (in the PPK section) - http://www.imfdb.org/wiki/Valkyrie

Other then that I have no other sources regarding the gun, but there are some mentions of the prosthesis (and how he chose not to wear it on the day he planted the bomb) all over the internet.