I know about the Non-Aggression pact that the Soviet Union and Nazi German signed as well as the spheres of influence they both set up in Eastern Europe, but I am looking for documentation and more information about the Soviet Union's attempt to join the Axis, especially in 1940, as it is to my understanding that Molotov visited Berlin on November 12, 1940 in order to discuss the USSR's official entry.

Other supporting information such as trade deals and research cooperation would also help, as it is to my understanding that the Soviet Union shipped raw materials to Germany which fueled the Wehrmacht, and am looking for more evidence of the such.

Thanks!