Baptism, Mithraic, 157; Taurobolium compared to, 70.
"The Oriental Religions in Roman Paganism" by Franz Cumont
There is no evidence of its existence either in Asia or in Italy before the taurobolium came into prominence (after A.D. 134).
"Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 6" by Various
Taurobolium, a sacrifice of expiation, very common in the third and fourth centuries.
"A Philosophical Dictionary, Volume 10 (of 10)" by François-Marie Arouet (AKA Voltaire)