@article{GDZPPN002351536,
title = {Boundaries for Natural Systems II.},
journal = {Mathematica Scandinavica},
volume = {30},
year = {1972},
pages = {281-289},
zbl = {0245.46079},
url = {http://dml.mathdoc.fr/item/GDZPPN002351536}
}
Brooks, R.M. Boundaries for Natural Systems II.. Mathematica Scandinavica, Tome 30 (1972) pp. 281-289. http://gdmltest.u-ga.fr/item/GDZPPN002351536/