References External links Crystal and Solid Contact Rectifiers 1909 publication describes experiments to determine the means of rectification (PDF file). Radio Detector Development from 1917 The Electrical Experimenter The Crystal Experimenters Handbook 1922 London publication devoted to point-contact diode detectors (PDF file courtesy of Lorne Clark via earlywireless.com) Patents - Oscillation detector (multiple metallic sulfide detectors), Clifford D. Babcock, 1908 - Oscillation detector and rectifier ("plated" silicon carbide detector with DC bias), G.W. Pickard, 1909 - Oscillation receiver (fractured surface red zinc oxide (zincite) detector), G.W. Pickard, 1909 - Oscillation device (iron pyrite detector), G.W. Pickard, 1909 - Oscillation detectors (paired dissimilar minerals), G.W. Pickard, 1914 History of radio Radio electronics Diodes Detectors Bangladeshi inventions Indian inventions