@book{knuth2011combinatorial,
  asin = {0201038048},
  author = {Knuth, Donald E.},
  dewey = {001.642},
  ean = {9780201038040},
  interhash = {276f5451e5ece797ff2c247aaa2866a8},
  intrahash = {481baec64f095b2555e780614e5c8f13},
  isbn = {0201038048},
  month = jan,
  publisher = {Addison-Wesley Professional},
  series = {The Art of Computer Programming},
  title = {Combinatorial Algorithms},
  url = {http://www.amazon.com/Art-Computer-Programming-Combinatorial-Algorithms/dp/0201038048/ref=sr_1_1/179-7432054-1264222?ie=UTF8&s=books&qid=1298901523&sr=8-1},
  volume = {4A},
  year = 2011
}

@book{knuth1989concrete,
  address = {Reading},
  author = {Graham, Ronald L. and Knuth, Donald E. and Patashnik, Oren},
  interhash = {a1450d7bb87f0107150d43a314a88326},
  intrahash = {ccef670ef39186763ecd379d2cca1e0a},
  publisher = {Addison-Wesley},
  title = {Concrete Mathematics: A Foundation for Computer Science},
  year = 1989
}