@unpublished{Linhard2005,
  author  = {Frank Linhard},
  title   = {{\"U}ber P.A.M. Diracs Beitrag zur Elektronentheorie},
  institution = {Physik},
  series    = {The IGN preprint series},
  number    = {33},
  pages     = {11},
  year    = {2005},
}