@article{1077490935,
author = {Risselman, W. C.},
title = {Approximation to the solution of a normal system of ordinary linear
differential equations},
journal = {Duke Math. J.},
volume = {4},
number = {1},
year = {1938},
pages = { 640-649},
language = {en},
url = {http://dml.mathdoc.fr/item/1077490935}
}
Risselman, W. C. Approximation to the solution of a normal system of ordinary linear
differential equations. Duke Math. J., Tome 4 (1938) no. 1, pp. 640-649. http://gdmltest.u-ga.fr/item/1077490935/