@article{compref54,
   author = {Blum,L and Blum,M},
   year = {1975},
   title = {Toward a Mathematical Theory of Inductive Inference},
   journal = {Information and Control},
   volume = {35},
   pages = {125-155}
}

@article{compref55,
   author = {Blum,M},
   year = {1967},
   title = {A Machine Independant Theory of the Complexity of Recursive Functions},
   journal = {Journal of the Association of Computing Machinery},
   volume = {14},
   pages = {322}
}