1. P. Drude, Ann. Phys., 1, 566–613, (1900). Ann. Phys., 3, 369–402, (1900).
2. Out of the Crystal Maze: Chapters from the History of Solid State Physics, by Lillian Hoddeson (Editor), Ernest Braun, Jurgen Teichmann, Spencer Weart (Editor), Frederick Seitz, Oxford Univ Press, (1992).
3. A. Einstein, Ann. Phys., 22, 180–190 (1907).
4. M. Born, T. von Kármán, Phys. Zs., 13, 297–309 (1912).
5. F. Bloch, Zeit. Phys., 52, 555–600, (1928).