Natura - nature Ref: C. Linnaeus, 1748: 210 actualia - actual entities Ref: A. Voltolini, 2006: 44 (note 19) [assumed position] Mundus Plinius - physical world Ref: C. Linnaeus, 1758: 5 [indirect position]; 24 Apr 2014. naturalia - natural bodies Ref: C. Linnaeus, 1758: 6 [implicit position] "crystal-kingdom" Ref: J.D. Dana, 1863: 1 [indirect position] chemical substances Ref: G.J. Leigh et al., 1998: 7 [implicit position] chemical compounds Ref: Wikimedia: 27 Sep 2009 Class selenonic acids [RSe(=O)2OH] Ref: G.P. Moss et al., 1995: 1365