A. V. Efimov ; Translated by Leonid Levant. A. V. Pogorelov ; translated from the Russian by Leonid Levant. A. V. Efimov, Yu. G. Zolotarev, V. M. Terpigoreva ; Translated by Leonid Levant. Eberhard Zeidler ; translated by Leo F. Boront. Kim, Donguk ;translated by Leon Hurvitz. Klaus Janich ; translated by Silvio Levy.