Column Descriptions

                                                                         
             Relative           Isotopic      Standard                   
Isotope      Atomic Mass        Composition   Atomic Weight    Notes     
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68  Er  162  161.9287884(20)    0.00139(5)    167.259(3)       g
        164  163.9292088(20)    0.01601(3)  
        166  165.9302995(22)    0.33503(36) 
        167  166.9320546(22)    0.22869(9)  
        168  167.9323767(22)    0.26978(18) 
        170  169.9354702(26)    0.14910(36) 
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