Instant controllability for Goursat problems
Pure Math. Appl. 12 (2001), no. 1, 51--65.
BibTex references
@Article\{GJ01,
author = "Gyurkovics, É. and Jank, Gerhard",
title = "Instant controllability for Goursat problems",
journal = "Pure Math. Appl.",
number = "1",
volume = "12",
pages = "51--65",
year = "2001",
}