Aaronson, Jon (1997). An introduction to infinite ergodic theory. Mathematical Surveys and Monographs. Vol. 50. Providence, Rhode Island: American Mathematical Society. p. 21. doi:10.1090/surv/050. ISBN0-8218-0494-4. MR1450400.
Aaronson, Jon (1997). An introduction to infinite ergodic theory. Mathematical Surveys and Monographs. Vol. 50. Providence, Rhode Island: American Mathematical Society. p. 21. doi:10.1090/surv/050. ISBN0-8218-0494-4. MR1450400.