Effect of the simultaneous substitution of two transition metals on the structural, magnetic and electrical properties of La0.6Sr0.4Mn1−2x Cr x Fe x O3 - Ben Abdelkhalek, Sonia; Kallel, Nabil; Kallel, Sami; Guizouarn, Thierry; Peña, Octavio; Oumezzine, Mohamed (Journal of Magnetism & Magnetic Materials, 2010)