Newton, Joseph Fort, The Builders, 1915. Cf. p.24. "The Grecian or Eleusinian Mysteries, established 1800 BC, represented Demeter and Persephone, and depicted the death of Dionysus with stately ritual which led the neophyte from death into life and immortality"
Ouvaroff, M. (alternatively given as Sergei Semenovich Uvarov, or Sergey Uvarov, 1786-1855) (Translated from the French by J. D. Price) Essay on the Mysteries of Eleusis, London : Rodwell and Martin, 1817 (Reprint: USA: Kessinger Publishing, 2004). Ouvaroff does write that fixing the earliest foundation date to the Eleusinian Mysteries is fraught with problems.
