[1] Schwarz Š.: A semigroup treatment of some theorems on non-negative matrices. Czechosl. Math. J. 15 (90) (1965), 212-229. MR 0175919 | Zbl 0232.20139

[2] Schwarz Š.: On the structure of the semigroup of stochastic matrices. Magyar tud. akad. Mat. kutató int. kőzl. 9 (1964), 297-311. MR 0188337 | Zbl 0143.03303

[3] Шварц Ш.: К теории хаусдорфовых бикомпактных полугрупп. Чехосл. мат. ж. 5 (80) (1955), 2-23. Zbl 1160.26300

[4] Schwarz Š.: A note on the structure of the semigroup of doubly stochastic matrices. Mat. časop. 17 (1967), 308-316. MR 0241451 | Zbl 0157.04902