Thomas Koshy, 80.48 The Euclidean Algorithm via Matrices and a Calculator, The Mathematical Gazette, Vol. 80, No. 489 (Nov., 1996), pp. 570-574 ...

The Euclidean algorithm offers a recipe for finding the greatest common divisor of two whole numbers. Suppose the given numbers are 12 and 18.

Niels Möller, On Schönhage's Algorithm and Subquadratic Integer GCD Computation, Mathematics of Computation, Vol. 77, No. 261 (Jan., 2008), pp. 589-607 ...