Platner, Samuel Ball. A Topographical Dictionary of Ancient Rome. London: Oxford UP, 1929. Print.
William Warde Fowler, The Religious Experience of the Roman People (London, 1922), p. 209. /wiki/William_Warde_Fowler
Auguraculum on the Quirinal: Varro, Lingua Latina, Book V
"An Elementary Manual of Roman Antiquities", (Griffin, 1859, from Harvard University), p. 64. https://books.google.com/books?id=f8spAAAAYAAJ&dq=roman+arx&pg=PA14
John Scheid, An Introduction to Roman Religion (Indiana University Press, 2003), pp. 113–114; Jerzy Linderski, "The Augural Law", Aufstieg und Niedergang der römischen Welt II.16 (1986), pp. 2164–2288, especially p. 2174 on the military auguraculum. /wiki/John_Scheid