A1 - Marciniak Andrzej A2 - Szyszka Barbara PB - OWN N2 - The paper presents one- and two-stage implicit interval methods of Runge-Kutta type. It is shown that the exact solution of the initial value problem belongs to interval-solutions obtained by both kinds of these methods. Moreover, some approximations of the widths of interval-solutions are given. L1 - http://lib.psnc.pl/Content/500/10.12921_cmst.1999.05.01.53-65_Marciniak.pdf L2 - http://lib.psnc.pl/Content/500 CY - PoznaƄ ER - T1 - ONE- AND TWO-STAGE IMPLICIT INTERVAL METHODS OF RUNGE-KUTTA TYPE UR - http://lib.psnc.pl/dlibra/docmetadata?id=500