Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class bismuthines [R3Bi]
                 1 "bismuthine"ᵀ [BiH3]
                 2 primary bismuthines [RBiH2 (R≠H)]
                 3 secondary bismuthines [R2BiH (R≠H)]
                 4 tertiary bismuthines [R3Bi (R≠H)]