@article{Helsper2006,
  author    = {Christoph Helsper},
  title     = {Measurement Techniques For Ultrafine Particles},
  journal   = {Ultrafine aerosols. Properties and behaviour. Proceedings of the 1. International Workshop on Ultrafine Aerosols of the Sonderforschungsbereich 209 'Stoff- und Energietransport in Aerosolen' -'Mass and energy transfer in aerosols'-, held at the Univ. of Duisburg on Sept. 29, 1986},
  year      = {2006},
}