Morrison at [1] Hogendijk, Jan P.; Berggren, J. L. Episodes in the Mathematics of Medieval Islam by J. Lennart Berggren. Journal of the American Oriental
}{2I(x,y)}}.} David A. Cox. The Arithmetic-Geometric Mean of Gauss. J.L. Berggren, Jonathan M. Borwein, Peter Borwein (编). Pi: A Source Book. Springer. 2004:
初,就可以作为已知最早的出处而极具重要性。 Elliot 2005, p. 583. As indicated by Jackson, The Earliest Surviving Scottish Poem. Berggren, J. Lennart and Alexander Jones. "Ptolemy's