Of the secondary cathode rays of the insulators.

[1] About the Refractive Indices of the De Broglie Waves of the Electron [J]. ZEITSCHRIFT FUR PHYSIK, 1928, 47 (5-6): : 417 - 421

[2] About Reflection Experiments by electrons in Insulators and its Interpretation by the Theory of Matter Waves [J]. ZEITSCHRIFT FUR PHYSIK, 1928, 48 (3-4): : 165 - 173

[3] Wehnelt A., 1925, ERG EXAKT NATURWISS, V4, P92

[1] About the Refractive Indices of the De Broglie Waves of the Electron [J]. ZEITSCHRIFT FUR PHYSIK, 1928, 47 (5-6): : 417 - 421

[2] About Reflection Experiments by electrons in Insulators and its Interpretation by the Theory of Matter Waves [J]. ZEITSCHRIFT FUR PHYSIK, 1928, 48 (3-4): : 165 - 173

[3] Wehnelt A., 1925, ERG EXAKT NATURWISS, V4, P92