To cite package 'msa' in publications use:

W. A. Obermeier, L. W. Lehnert, C. I. Kammann, C. M\"{u}ller, L. Gr\"{u}nhage, J. Luterbacher, M. Erbs, G. Moser, R. Seibert, N. Yuan, J. Bendix (under review) Reduced CO2 fertilization in temperate C3 grasslands under more extreme weather conditions. Nature Climate Change

Corresponding BibTeX entry:

  @Article{,
    title = {Reduced CO2 fertilization in temperate C3 grasslands under
      more extreme weather conditions},
    author = {W. A. Obermeier and L. W. Lehnert and C. I. Kammann and
      C. M\"{u}ller and L. Gr\"{u}nhage and J. Luterbacher and M. Erbs
      and G. Moser and R. Seibert and N. Yuan and J. Bendix},
    year = {under review},
    journal = {Nature Climate Change},
  }