@article{10_1090_S0894_0347_08_00604_8,
     author = {Cholak, Peter and Downey, Rodney and Harrington, Leo},
     title = {On the orbits of computably enumerable sets},
     journal = {Journal of the American Mathematical Society},
     pages = {1105--1135},
     publisher = {mathdoc},
     volume = {21},
     number = {4},
     year = {2008},
     doi = {10.1090/S0894-0347-08-00604-8},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-08-00604-8/}
}