Freitas, F. L. (2023), "Solution of the Basel problem using the Feynman integral trick", arXiv:2312.04608 [math.CA]
Connon, D. F. (2007), "Some series and integrals involving the Riemann zeta function, binomial coefficients and the harmonic numbers (Volume I)", arXiv:0710.4022 [math.HO]
Johan Wästlund (December 8, 2010). "Summing Inverse Squares by Euclidean Geometry"(PDF). Chalmers University of Technology. Department of Mathematics, Chalmers University. Retrieved 2024-10-11.