Ken Yamamura  
                                   (2001)   
                
                
                    
                        
                            
            In the previous paper [15], we determined the structure of the Galois groups  of the maximal unramified extensions  of imaginary quadratic number fields  of conductors  under the Generalized Riemann Hypothesis (GRH) except for 23 fields (these are of conductors ) and give a table of . We update the table (under GRH). For 19 exceptional fields  of them, we determine . In particular, for , we obtain , the fourth Hilbert class field of . This is the first example of a number...