@article{GDZPPN002044102,
title = {Measures of centrality and complexity for partial propositional calculi.},
journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
volume = {15},
year = {1972},
pages = {7-18},
zbl = {0248.02018},
url = {http://dml.mathdoc.fr/item/GDZPPN002044102}
}
Chapin, E. William. Measures of centrality and complexity for partial propositional calculi.. Archiv für mathematische Logik und Grundlagenforschung, Tome 15 (1972) pp. 7-18. http://gdmltest.u-ga.fr/item/GDZPPN002044102/