@article{van_der_Poorten_1979,
    doi = {10.1007/bf03028234},
    url = {https://doi.org/10.1007%2Fbf03028234},
    year = {1979},
    month = {dec},
    publisher = {Springer Science and Business Media {LLC}},
    volume = {1},
    number = {4},
    pages = {195--203},
    author = {Alfred van der Poorten and R. Ap{\'{e}}ry},
    title = {A proof that Euler missed ...},
    journal = {The Mathematical Intelligencer}
}

@article{van_der_Poorten_1979, doi = {10.1007/bf03028234}, url = {https://doi.org/10.1007%2Fbf03028234}, year = {1979}, month = {dec}, publisher = {Springer Science and Business Media {LLC}}, volume = {1}, number = {4}, pages = {195--203}, author = {Alfred van der Poorten and R. Ap{\'{e}}ry}, title = {A proof that Euler missed ...}, journal = {The Mathematical Intelligencer} }