A Recipe for Echoes

          @misc{ scivideos_PIRSA:17110076,
            doi = {10.48660/17110076},
            url = {https://pirsa.org/17110076},
            author = {Zimmerman, Aaron},
            keywords = {Quantum Gravity},
            language = {en},
            title = {A Recipe for Echoes},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2017},
            month = {nov},
            note = {PIRSA:17110076 see, \url{https://scivideos.org/index.php/pirsa/17110076}}
          }