@article{GDZPPN002474271,
title = {A Boundedness Theorem for a Nonlinear, Nonautonomous System.},
journal = {Monatshefte f\"ur Mathematik},
volume = {68},
year = {1964},
pages = {46-51},
zbl = {0122.09305},
url = {http://dml.mathdoc.fr/item/GDZPPN002474271}
}
Petty, C.M.; Leitmann, G. A Boundedness Theorem for a Nonlinear, Nonautonomous System.. Monatshefte für Mathematik, Tome 68 (1964) pp. 46-51. http://gdmltest.u-ga.fr/item/GDZPPN002474271/