@InCollection{korovin99a,
  author        = {Korovin,K.},
  title         = {Compositions of permutations and algorithmic reducibilities},
  booktitle     = {Recursion Theory and Complexity},
  series        = {de Gruyter Series in Logic and Applications 2}
  publisher     = {Walter de Gruyter},
  editor        =  { Arslanov, M. and Lempp, S.},
  pages         = {89--95},
    year        = {1999}
}