@article{01209886,
title = {On the existence of nonnegative solutions of the periodic boundary value problem for a system of linear generalized ordinary differential equations.},
journal = {Memoirs on Differential Equations and Mathematical Physics},
volume = {12},
year = {1997},
pages = {153-156},
zbl = {0939.34506},
language = {en},
url = {http://dml.mathdoc.fr/item/01209886}
}
Ashordia, M. On the existence of nonnegative solutions of the periodic boundary value problem for a system of linear generalized ordinary differential equations.. Memoirs on Differential Equations and Mathematical Physics, Tome 12 (1997) pp. 153-156. http://gdmltest.u-ga.fr/item/01209886/