To cite biocharkitgui in publications use:

  Sarkar, S. (2026). biocharkitgui: Shiny GUI for the 'biocharkit'
  Biochar Analysis Toolkit. R package version 0.3.1.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {biocharkitgui: Shiny GUI for the 'biocharkit' Biochar Analysis Toolkit},
    author = {Sukamal Sarkar},
    year = {2026},
    note = {R package version 0.3.1},
  }

Please also cite the underlying 'biocharkit' package, e.g. via
citation("biocharkit").