1. A. A. Markov, “Extension of the law of large numbers to dependent quantities,” Izv. Fiz.-Mat. O-va. Kazan. Univ., Ser. 2 15 (4), 135–156 (1906); A. A. Markov, Selected Works (Akad. Nauk SSSR, Leningrad, 1951), pp. 339–361 [in Russian].
2. A. A. Markov, “Investigation of the general case of trials associated into a chain,” Zap. Akad. Nauk (S.-Peterb.) Fiz.-Matem. Otd., Ser. 8 25 (3), 1–33 (1910); A. A. Markov, Selected Works (AN SSSR, Leningrad, (Akad. Nauk SSSR, Leningrad, 1951), pp. 465–507 [in Russian].
3. S. N. Bernstein, Collected Works (Nauka, Moscow, 1964), Vol. 4 [in Russian].
4. N. A. Sapogov, “On singular Markov chains,” Dokl. Akad. Nauk SSSR (N. S.) 58, 193–196 (1947).
5. Yu. V. Linnik, “On the theory of nonuniform Markov chains,” Izv. Akad. Nauk SSSR. Ser. Mat. 13, 65–94 (1949).