To cite effects in publications use:

  John Fox and Sanford Weisberg (2019). An R Companion to Applied
  Regression, 3rd Edition. Thousand Oaks, CA
  <https://www.john-fox.ca/Companion/index.html>

A BibTeX entry for LaTeX users is

  @Book{,
    title = {An R Companion to Applied Regression},
    edition = {3rd},
    author = {John Fox and Sanford Weisberg},
    year = {2019},
    publisher = {Sage},
    address = {Thousand Oaks CA},
    url = {https://www.john-fox.ca/Companion/index.html},
  }

For predictor effects or partial residuals also cite:

  John Fox, Sanford Weisberg (2018). Visualizing Fit and Lack of Fit in
  Complex Regression Models with Predictor Effect Plots and Partial
  Residuals. Journal of Statistical Software, 87(9), 1-27. doi
  10.18637/jss.v087.i09

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Visualizing Fit and Lack of Fit in Complex Regression Models with Predictor Effect Plots and Partial Residuals},
    author = {John Fox and Sanford Weisberg},
    journal = {Journal of Statistical Software},
    year = {2018},
    volume = {87},
    number = {9},
    pages = {1--27},
    doi = {10.18637/jss.v087.i09},
  }

For generalized linear models also cite:

  John Fox (2003). Effect Displays in R for Generalised Linear Models.
  Journal of Statistical Software, 8(15), 1-27. doi
  10.18637/jss.v008.i15

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Effect Displays in {R} for Generalised Linear Models},
    author = {John Fox},
    journal = {Journal of Statistical Software},
    year = {2003},
    volume = {8},
    number = {15},
    pages = {1--27},
    doi = {10.18637/jss.v008.i15},
  }

For usage in multinomial and proportional-odds logit models also cite:

  John Fox, Jangman Hong (2009). Effect Displays in R for Multinomial
  and Proportional-Odds Logit Models: Extensions to the effects
  Package. Journal of Statistical Software, 32(1), 1-24. doi
  10.18637/jss.v032.i01

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Effect Displays in {R} for Multinomial and Proportional-Odds Logit Models: Extensions to the {effects} Package},
    author = {John Fox and Jangman Hong},
    journal = {Journal of Statistical Software},
    year = {2009},
    volume = {32},
    number = {1},
    pages = {1--24},
    doi = {10.18637/jss.v032.i01},
  }