Development of low frequency ferrite core materials using magnetite, a beach sand mineral / Shireen Akhter [PhD Thesis] Akhter, Shireen Ferrimagnetism 538.45 AKD Thesis (Ph.D.) -- Department of Applied Physics, Electronics & Communication Engineering, University of Dhaka, 2010-2011 Includes Bibliographical references Dhaka : University of Dhaka, 2014. 2014. 2014 Text xix, 162 p. : eng