1. Aritmetisk-geometrisko medelvärdet och ellipsens båglängd;Almkvist;Nordisk Mat. Tidskr.,1978
2. Gauss, Landen, Ramanujan, the arithmetic–geometric mean, ellipses, and the Ladies Diary;Almkvist;Amer. Math. Monthly,1988
3. Are π, e and 2 equally difficult to compute?;Baxter;Amer. Math. Monthly,1981
4. Pi: A Source Book,1997
5. Opera I;Bernoulli,1744