@unpublished{njpls2005,
 author = {J. M. Siskind},
 title = {Backpropagation Through Functional Programs: How to do Reverse-Mode AD
          Correctly in a Functional Framework},
 location = {New Jersey Programming Languages and Systems (NJPLS)},
 date = 16,
 month = sep,
 year = 2005,
 url = {http://engineering.purdue.edu/~qobi/tweet-talks/njpls2005-slides.pdf}}