@incollection{Swierstra_2009,
    doi = {10.1007/978-3-642-03359-9_30},
    url = {https://doi.org/10.1007%2F978-3-642-03359-9_30},
    year = {2009},
    publisher = {Springer Berlin Heidelberg},
    pages = {440--451},
    author = {Wouter Swierstra},
    title = {A Hoare Logic for the State Monad},
    booktitle = {Lecture Notes in Computer Science}
}

@incollection{Swierstra_2009, doi = {10.1007/978-3-642-03359-9_30}, url = {https://doi.org/10.1007%2F978-3-642-03359-9_30}, year = {2009}, publisher = {Springer Berlin Heidelberg}, pages = {440--451}, author = {Wouter Swierstra}, title = {A Hoare Logic for the State Monad}, booktitle = {Lecture Notes in Computer Science} }