Unitarity in the Presence of Closed Timelike Curves

          @misc{ scivideos_PIRSA:05100008,
            doi = {10.48660/05100008},
            url = {https://pirsa.org/05100008},
            author = {Cornalba, Lorenzo},
            keywords = {Cosmology},
            language = {en},
            title = {Unitarity in the Presence of Closed Timelike Curves},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2005},
            month = {oct},
            note = {PIRSA:05100008 see, \url{https://scivideos.org/pirsa/05100008}}
          }