JF Ptak Science Books Reference Tools series
Here's a very useful tool for the early days of nuclear fission and atomic energy--the bibliography from William Stephen's Nuclear Fission and Atomic Energy (published by the Science Press in 1948). The OCR is a little unsteady but the info is there even if it isn't as clear as it might be.
Also see the excellent Louis Turner bibliography for nuclear fission, 1934-1940 (133 items) in an earlier post on this blog, here: http://longstreet.typepad.com/thesciencebookstore/2013/08/turners-bibliographic-review-of-nuclear-fission-1934-1940.html
Partial Bibliography on Nuclear Fission and Transuranic Elements
Full text here: https://archive.org/stream/nuclearfissionan030064mbp/nuclearfissionan030064mbp_djvu.tx
(Not all these references were consulted by the authors and the references in the text are not all included in this bibliography.) M. Ageno, E. Amaldi, D. Bocciarelli, B. Cacciapuoti and G. Trabacchi, Ricerca Sci. 11, 302 (1940), "Fission of heavy elements.'' M. Ageno, E. Amaldi, D. Bocciarelli and G. Trabacchi, Ricerca Sci. 11, 413 (1940, "The decomposition of U with fast neutrons." M. Ageno, E. Amaldi, D. Bocciarelli, B. Cacciapuoti and G. Trabac- chi, Phys. Rev. 60, 67 (1941), "Fission yield by fast neutrons."