@article{702188,
title = {On a certain extension of the maximum principle},
booktitle = {Differential Equations and Their Applications},
series = {GDML\_Books},
publisher = {Publishing House of the Czechoslovak Academy of Sciences},
address = {Prague},
year = {1963},
pages = {223-228},
mrnumber = {MR0173860},
zbl = {0145.36703},
url = {http://dml.mathdoc.fr/item/702188}
}
Výborný, R. On a certain extension of the maximum principle, dans Differential Equations and Their Applications, GDML_Books, (1963), pp. 223-228. http://gdmltest.u-ga.fr/item/702188/