@article{HelsperFissan1983,
  author    = {Helsper, Christoph and Fißan, H. J.},
  title     = {Calibration of the Polytec HC-15 and HC-70 Optical Particle Counters / Fißan, H. J. ; Helsper, C.},
  series = {Aerosols in the mining and industrial work environments, Vol. 3. Instrumentation, Marple, Virgil A. ; Liu, Benjamin Y.},
  journal   = {Aerosols in the mining and industrial work environments, Vol. 3. Instrumentation, Marple, Virgil A. ; Liu, Benjamin Y.},
  publisher = {Ann Arbor Science},
  address   = {Ann Arbor, Mich.},
  pages     = {825 -- 829},
  year      = {1983},
  language  = {en}
}
@article{HelsperFissanKasper1984,
  author    = {Helsper, Christoph and Fißan, H. J. and Kasper, W.},
  title     = {Kalibrierung der Partikelgr{\"o}ßenbestimmung von optischen Partikelz{\"a}hlern / Fißan, H. J.; Helsper, C. ; Kasper, W.},
  series = {3. Europ{\"a}isches Symposion Partikelmeßtechnik : [PARTEC, eine Veranstaltung der Reihe Partikel-Technologie N{\"u}rnberg ; N{\"u}rnberg, 9. - 11. Mai 1984 ; preprints] = 3. European Symposium on Particle Characterization / Veranst.: GVC, Gesellschaft Verfahrenstechnik und Chemieingenieurwesen im Verein Deutscher Ingenieure (VDI). Red. Bearb.: Kurt Leschonski},
  journal   = {3. Europ{\"a}isches Symposion Partikelmeßtechnik : [PARTEC, eine Veranstaltung der Reihe Partikel-Technologie N{\"u}rnberg ; N{\"u}rnberg, 9. - 11. Mai 1984 ; preprints] = 3. European Symposium on Particle Characterization / Veranst.: GVC, Gesellschaft Verfahrenstechnik und Chemieingenieurwesen im Verein Deutscher Ingenieure (VDI). Red. Bearb.: Kurt Leschonski},
  publisher = {NMA N{\"u}rnberger Messe- und Ausstellungsges.},
  address   = {N{\"u}rnberg},
  pages     = {263 -- 274},
  year      = {1984},
  language  = {de}
}
@article{HelsperFissanThielen1983,
  author    = {Helsper, Christoph and Fißan, H. J. and Thielen, H. J.},
  title     = {Determination of Particle Size Distributions by Means of an Electrostatic Classifier / Fißan, H. J.; Helsper, C. ; Thielen, H. J.},
  series = {Journal of Aerosol Science. 14 (1983), H. 3},
  journal   = {Journal of Aerosol Science. 14 (1983), H. 3},
  isbn      = {0021-8502},
  pages     = {354 -- 357},
  year      = {1983},
  language  = {en}
}
@article{HelsperFissanKasper1984,
  author    = {Helsper, Christoph and Fißan, H. J. and Kasper, W.},
  title     = {Calibration of Optical Particle Counters with Respect to Particle Size / Fißan, H. J. ; Helsper, C.; Kasper, W.},
  series = {Particle and Particle Systems Characterization. 1 (1984), H. 1984},
  journal   = {Particle and Particle Systems Characterization. 1 (1984), H. 1984},
  isbn      = {1521-4117},
  pages     = {108 -- 111},
  year      = {1984},
  language  = {en}
}
@article{HelsperBartzFissanetal.1985,
  author    = {Helsper, Christoph and Bartz, H. and Fißan, H. J. and Kousaka, Y. (u.a.)},
  title     = {Response Characteristics for Four Condensation Nucleus Counters to Particles in the 3 to 50 nm Diameter Range / Bartz, H. ; Fißan, H. J. ; Helsper, C.; Kousaka, Y. ; Okuyama, K. ; Keady, R. Fruin, S. ; McMurry, P. H.; Pui, D. Y. H. ; Stolzenburg, M. R.},
  series = {Journal of Aerosol Science. 16 (1985), H. 5},
  journal   = {Journal of Aerosol Science. 16 (1985), H. 5},
  isbn      = {0021-8502},
  pages     = {443 -- 456},
  year      = {1985},
  language  = {en}
}