To cite the pressure-correction method that 'appac' implements, please
cite the original works:

  Boček P, Novák J, Janák J (1969). “Effect of pressure on the
  performance of the flame ionization detector.” _Journal of
  Chromatography A_, *43*, 431-436. doi:10.1016/S0021-9673(00)99223-9
  <https://doi.org/10.1016/S0021-9673%2800%2999223-9>.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Effect of pressure on the performance of the flame ionization detector},
    author = {P. Boček and J. Novák and J. Janák},
    journal = {Journal of Chromatography A},
    year = {1969},
    volume = {43},
    pages = {431--436},
    doi = {10.1016/S0021-9673(00)99223-9},
  }

  Ayers B, Clardy E (1985). “Pressure Compensation for a
  Chromatograph.” US Patent 4,512,181,
  <https://patents.google.com/patent/US4512181A>.

A BibTeX entry for LaTeX users is

  @Misc{,
    title = {Pressure Compensation for a Chromatograph},
    author = {B. O. Ayers and E. K. Clardy},
    year = {1985},
    note = {US Patent 4,512,181},
    url = {https://patents.google.com/patent/US4512181A},
  }

  Agilent Technologies (2005). “The importance of area and retention
  time precision in gas chromatography.” Technical Note 5989-3425EN,
  Agilent Technologies.
  <https://www.agilent.com/cs/library/technicaloverviews/public/5989-3425EN.pdf>.

A BibTeX entry for LaTeX users is

  @TechReport{,
    title = {The importance of area and retention time precision in gas chromatography},
    author = {{Agilent Technologies}},
    institution = {Agilent Technologies},
    type = {Technical Note},
    number = {5989-3425EN},
    year = {2005},
    url = {https://www.agilent.com/cs/library/technicaloverviews/public/5989-3425EN.pdf},
  }