by J. J. Jakosky. by M. N. Pokrovsky. by N. N. Baransky. by R. A. Ulyanovsky. by B. M. Letsky. by I. G. Petrovsky. by E. I. Radzimovsky. by V. A. Riasanovsky. by V. G. Belinsky. by J. V. Uspensky.