@unpublished{nips2016b,
 author = {J. M. Siskind},
 title = {The tension between convenience and performance in automatic
          differentiation},
 location = {NIPS Workshop on The Future of Gradient-Based Machine
             Learning Software},
 date = 10,
 month = dec,
 year = 2016}
 url = {http://engineering.purdue.edu/~qobi/tweet-talks/nips2016b-slides.pdf}}