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[Elg61] Calvin C. Elgot. Decision problems of finite automata design and related arithmetics. Transactions of the American Mathematical Society 98(1):21-51. American Mathematical Society, January 1961. 
@article{TAMS98(1)-Elg,
  author =              {Elgot, Calvin C.},
  title =               {Decision problems of finite automata design and
                         related arithmetics},
  publisher =           {American Mathematical Society},
  journal =             {Transactions of the American Mathematical Society},
  volume =              {98},
  number =              {1},
  pages =               {21-51},
  year =                {1961},
  month =               jan,
  doi =                 {10.2307/1993511},
}
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