@article{Pettorossi_1985,
    doi = {10.1007/bf01934378},
    url = {https://doi.org/10.1007%2Fbf01934378},
    year = {1985},
    month = {jun},
    publisher = {Springer Science and Business Media {LLC}},
    volume = {25},
    number = {2},
    pages = {327--334},
    author = {Alberto Pettorossi},
    title = {Towers of Hanoi problems: Deriving iterative solutions by program transformations},
    journal = {{BIT} Numerical Mathematics}
}

@article{Pettorossi_1985, doi = {10.1007/bf01934378}, url = {https://doi.org/10.1007%2Fbf01934378}, year = {1985}, month = {jun}, publisher = {Springer Science and Business Media {LLC}}, volume = {25}, number = {2}, pages = {327--334}, author = {Alberto Pettorossi}, title = {Towers of Hanoi problems: Deriving iterative solutions by program transformations}, journal = {{BIT} Numerical Mathematics} }