TY - JOUR TI - New first-order conservation laws for the electromagnetic field PY - 1988 AU - Ragusa, Silvestre T2 - Nuovo Cimento B DO - 10.1007/bf02828074 UR - https://doi.org/10.1007/bf02828074 PP - Bologna VL - 101 IS - 1 SP - 121-4 IS - ja 1988 ER -