[1] Frej, Bartosz. Transition probabilities and transition systems. 1st Conference for Young Mathematicians (Polish) (Karpacz, 2000). Prace Nauk. Inst. Mat. Politech. Wroc\l aw. Ser. Konfer. 24 (2000), no. 3, 45--53

[2] Frej, Bartosz. A note on Markov operators and transition systems. Colloq. Math. 91 (2002), no. 2, 183--190.

[3] Downarowicz, Tomasz; Frej, Bartosz. Measure-theoretic and topological entropy of operators on function spaces. Ergodic Theory Dynam. Systems 25 (2005), no. 2, 455--481.

[4] Frej, Bartosz. Maličky-Riečan's entropy as a version of operator entropy. Fundam. Math. 189 (2006), No. 2, 185-193

[5] Frej, Bartosz; Kwaśnicka, Agata. Minimal models for Z^d-actions. Colloq. Math. 110 (2008), No. 2, 461-476

[6] Frej, Bartosz. I jeszcze jeden, i jeszcze raz. Matematyka, Społeczeństwo, Nauczanie, 41 (VII 2008),

[7] Frej, Bartosz; Frej, Paulina. An integral formula for entropy of doubly stochastic operators. Fund. Math. 213 (2011), 271-289

[8] Frej, Bartosz; Frej, Paulina. The Shannon-McMillan theorem for doubly stochastic operators. Nonlinearity. (2012)

[9] Downarowicz Tomasz; Frej, Bartosz; Romagnoli, Pierre-Paul. Shearer's inequality and infimum rule for Shannon entropy and topological entropy. Contemporary Mathematics, 669 (2016)

[10] Frej, Bartosz; Kwaśnicka, Agata. A map maintaining the orbits of a given Z^d-action. Colloq. Math. 143 (2016), No. 1, 1-15

[11] Frej, Bartosz; Huczek, Dawid. Minimal models for actions of amenable groups. Groups Geom. Dyn. 11 (2017), 567-583

[12] Frej, Bartosz; Huczek, Dawid. Faces of simplices of invariant measures for actions of amenable groups. To appear in Monatshefte fur Mathematik