Differential Equations - Lecture 3

          @misc{ pirsa_PIRSA:11080142,
            doi = {},
            url = {https://pirsa.org/11080142},
            author = {Croke, Sarah},
            keywords = {Mathematical physics},
            language = {en},
            title = {Differential Equations - Lecture 3},
            publisher = {Perimeter Institute},
            year = {2011},
            month = {aug},
            note = {PIRSA:11080142 see, \url{https://pirsa.org}}
          }