To cite package ‘nasapower’ in publications use:

  Sparks A (2018). “nasapower: A NASA POWER Global Meteorology, Surface
  Solar Energy and Climatology Data Client for R.” _The Journal of Open
  Source Software_, *3*(30), 1035. doi:10.21105/joss.01035
  <https://doi.org/10.21105/joss.01035>.

A BibTeX entry for LaTeX users is

  @Article{,
    author = {Adam H. Sparks},
    title = {nasapower: A NASA POWER Global Meteorology, Surface Solar Energy and Climatology Data Client for R},
    doi = {10.21105/joss.01035},
    year = {2018},
    month = {oct},
    publisher = {The Open Journal},
    volume = {3},
    number = {30},
    pages = {1035},
    journal = {The Journal of Open Source Software},
  }