Jameson, G.J.O. (2014). «Inequalities for the perimeter of an ellipse». Mathematical Gazette (em inglês). 98 (499): 227–234. JSTOR3621497. doi:10.2307/3621497
Almkvist, Gert; Berndt, Bruce (1988), «Gauss, Landen, Ramanujan, the arithmetic-geometric mean, elipses, π, e o Ladies Diary», American Mathematical Monthly, 95 (7): 585-608, JSTOR2323302, MR966232, doi:10.2307/2323302
jstor.org
Jameson, G.J.O. (2014). «Inequalities for the perimeter of an ellipse». Mathematical Gazette (em inglês). 98 (499): 227–234. JSTOR3621497. doi:10.2307/3621497
Almkvist, Gert; Berndt, Bruce (1988), «Gauss, Landen, Ramanujan, the arithmetic-geometric mean, elipses, π, e o Ladies Diary», American Mathematical Monthly, 95 (7): 585-608, JSTOR2323302, MR966232, doi:10.2307/2323302