Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class amidrazones [RC(=NH)NHNH2, RC(NH2)=NNH2]
                 1 Class hydrazide imides [RC(=NH)NHNH2]
                 2 Class amide hydrazones [RC(NH2)=NNH2]