Congruences and Complexes of Circles
J. L. Coolidge · Transactions of the American Mathematical Society · 1914
Our groups of equations ( 8) and ( 9) lead to easy proofs of all the classical * The concept of paratactic circles seems first to have been introduced in an article by the Author, A Study of the Circle Cross, These Transactions, vol.14 (1913), pp.149-174.Proofs of our theorems A-D will there be found.