@article{1183536255,
author = {Zettl, Anton},
title = {A constructive characterization of disconjugacy},
journal = {Bull. Amer. Math. Soc.},
volume = {81},
number = {4},
year = {1975},
pages = { 145-147},
language = {en},
url = {http://dml.mathdoc.fr/item/1183536255}
}
Zettl, Anton. A constructive characterization of disconjugacy. Bull. Amer. Math. Soc., Tome 81 (1975) no. 4, pp. 145-147. http://gdmltest.u-ga.fr/item/1183536255/