@article{HelsperFissan2006,
  author    = {Christoph Helsper and H. J. Fißan},
  title     = {Calibration of the Polytec HC-15 and HC-70 Optical Particle Counters / Fißan, H. J. ; Helsper, C.},
  journal   = {Aerosols in the mining and industrial work environments, Vol. 3. Instrumentation, Marple, Virgil A. ; Liu, Benjamin Y.},
  pages     = {825 -- 829},
  year      = {2006},
}