@article{1102978701,
author = {Jockusch, C. G. and McLaughlin, T. G.},
title = {Countable retracing functions and $\Pi\_2{}^0$ predicates.},
journal = {Pacific J. Math.},
volume = {31},
number = {3},
year = {1969},
pages = { 67-93},
language = {en},
url = {http://dml.mathdoc.fr/item/1102978701}
}
Jockusch, C. G.; McLaughlin, T. G. Countable retracing functions and $\Pi_2{}^0$ predicates.. Pacific J. Math., Tome 31 (1969) no. 3, pp. 67-93. http://gdmltest.u-ga.fr/item/1102978701/