Valeryi Alekseevich Letyaev, Y. Y. G. V. A. S., and S. Yulia Sergeevna Manina. “Soviet-Hungarian Relationships on the Threshold of the Great Patriotic War”. Opción, Vol. 35, Dec. 2019, pp. 198-16, https://mail.produccioncientificaluz.org/index.php/opcion/article/view/30039.