@article{HelsperDreilingHalleretal.1986,
  author    = {Helsper, Christoph and Dreiling, V. and Haller, P. and Kaminski, U.},
  title     = {Intercomparison of Eleven Condensation Nucleus Counters / Dreiling, V. ; Haller, P. ; Helsper, C.; Kaminski, U. ; Plomp, A. ; Raes, F. ; Roth, C. ; Schier, J. ; Sch{\"u}rmann, G.},
  series = {Journal of Aerosol Science. 17 (1986), H. 3},
  journal   = {Journal of Aerosol Science. 17 (1986), H. 3},
  isbn      = {0021-8502},
  pages     = {565 -- 570},
  year      = {1986},
  language  = {en}
}
@article{HelsperMoelterHaller1990,
  author    = {Helsper, Christoph and M{\"o}lter, W. and Haller, P.},
  title     = {Representative Dilution of Aerosols by a Factor of 10,000},
  series = {Journal of Aerosol Science. 21 (1990), H. Suppl. 1},
  journal   = {Journal of Aerosol Science. 21 (1990), H. Suppl. 1},
  isbn      = {0021-8502},
  pages     = {637 -- 640},
  year      = {1990},
  language  = {en}
}