${{\mathit n}}$ ELECTRIC DIPOLE MOMENT 
INSPIRE search
 A nonzero value is forbidden by both $\mathit T$ invariance and $\mathit P$ invariance. A number of early results have been omitted. See 
RAMSEY 1990, 
GOLUB 1994, and 
LAMOREAUX 2009 for reviews. 
 The results are upper limits on $\vert {{\mathit d}_{{{n}}}}\vert $.