首页 / 官方藏书 / Philipp Reis: Inventor of the Telephone / A Biographical Sketch / APPENDIX II. On the Variation of Electric Resistance at a Point of Imperfect Contact in a Circuit.
首页 / 官方藏书 / Philipp Reis: Inventor of the Telephone / A Biographical Sketch / APPENDIX II. On the Variation of Electric Resistance at a Point of Imperfect Contact in a Circuit.