Investigations on the effect of ageing on charge de-trapping processes of epoxy–alumina nanocomposites based on isothermal relaxation current measurements oleh Subhajit Maur, Nasirul Haque, Nasirul Haque, Preetha Pottekat, Biswajit Chakraborty, Sovan Dalai, Sovan Dalai, Biswendu Chatterjee