@article{DBLP:journals/jsyml/HajekK89,
author = {Petr H{\'a}jek and
Anton\'{\i}n Kucera},
title = {On Recursion Theory in I Sigma$_{\mbox{1}}$},
journal = {J. Symb. Log.},
volume = {54},
number = {2},
year = {1989},
pages = {576-589},
ee = {http://projecteuclid.org/euclid.jsl/1183742928},
bibsource = {DBLP, http://dblp.uni-trier.de}
}