A. Firestone, "A new analogy between mechanical and electrical systems", "Journal of the Acoustical Society of America", vol.4, pp.249–267 (1932–1933).</ref>لم يكن تطوير تماثل ميكانيكي أمرًا كافيًا.
A. Firestone, "A new analogy between mechanical and electrical systems", "Journal of the Acoustical Society of America", vol.4, pp.249–267 (1932–1933).</ref>It was not enough to just develop a mechanical analogy.