D. Davidson, L. A. Welo, The nature of Prussian blue. J. Phys. Chem. 32, 1191–1196 (1928). J. F. Keggin, F. D. Miles, Structures and Formulæ of the Prussian blues and related compounds. Nature 137, 577–578 (1936). M. B. Robin, The color and electronic configurations of Prussian blue. Inorg. Chem. 1, 337–342 (1962). D. Ellis, M. Eckhoff, V. D. Neff, Electrochromism in the mixed-valence hexacyanides. 1. Voltammetric and spectral studies of the oxidation and reduction of thin films of Prussian blue. J. Phys. Chem.