F. Cajori, William Oughtred, a Great Seventeenth-Century Teacher of Mathematics (Open Court Publishing Company, Chicago 1916), pp. 12-14 (Internet Archive).
'Oughtred (William)', in P. Bayle, translated and revised by J.P. Bernard, T. Birch and J. Lockman, A General Dictionary, Historical and Critical, (James Bettenham, for G. Strachan and J. Clarke, London 1734/1739), Vol. VIII, pp. 77-86 (Google).