L. D. Landau and S. I. Pekar, Effective mass of a polaron, Zh. Eksp. Teor. Fiz. 18, 419–423 (1948) [in Russian], English translation: Ukr. J. Phys., Special Issue, 53, p.71-74 (2008), "Archived copy"(PDF). Archived from the original(PDF) on 2016-03-05. Retrieved 2016-08-10.{{cite web}}: CS1 maint: archived copy as title (link)
L. D. Landau and S. I. Pekar, Effective mass of a polaron, Zh. Eksp. Teor. Fiz. 18, 419–423 (1948) [in Russian], English translation: Ukr. J. Phys., Special Issue, 53, p.71-74 (2008), "Archived copy"(PDF). Archived from the original(PDF) on 2016-03-05. Retrieved 2016-08-10.{{cite web}}: CS1 maint: archived copy as title (link)