To cite package 'cardidates' in publications use:

  Rolinski, S., Horn, H., Petzoldt, T., Paul, L. (2007). Identification
  of cardinal dates in phytoplankton time series to enable the analysis
  of long-term trends. Oecologia 153, 997--1008.
  doi:10.1007/s00442-007-0783-2

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Identifying cardinal dates in phytoplankton time series to
    enable the analysis of long-term trends},
    author = {{Susanne Rolinski} and {Heidemarie Horn} and {Thomas Petzoldt} and {Lothar Paul}},
    journal = {Oecologia},
    year = {2007},
    volume = {153},
    pages = {997--1008},
    number = {4},
    doi = {10.1007/s00442-007-0783-2},
    keywords = {Spring mass development, Climate change, Saidenbach
    Reservoir, Limnology, Physical-biological coupling, Peak
    detection},
  }