@incollection{Sipser,
    doi = {10.1007/bfb0030341},
    url = {https://doi.org/10.1007%2Fbfb0030341},
    publisher = {Springer-Verlag},
    pages = {567--572},
    author = {Michael Sipser},
    title = {A topological view of some problems in complexity theory},
    booktitle = {Mathematical Foundations of Computer Science 1984}
}

@incollection{Sipser, doi = {10.1007/bfb0030341}, url = {https://doi.org/10.1007%2Fbfb0030341}, publisher = {Springer-Verlag}, pages = {567--572}, author = {Michael Sipser}, title = {A topological view of some problems in complexity theory}, booktitle = {Mathematical Foundations of Computer Science 1984} }