@book{surreal,
   author = "Donald E. Knuth",
   title = "Surreal Numbers",
   year = 1974,
   publisher = "Addison-Wesley",
   address = "Reading, Massachusetts"
}

@book{concrete-math,
   author = "Ronald L. Graham and Donald E. Knuth and Oren Patashnik",
   title = "Concrete Mathematics",
   year = 1989,
   publisher = "Addison-Wesley",
   address = "Reading, Massachusetts"
}