To cite the cobs package in publications use:

Ng PT, Maechler M (2025). COBS – Constrained B-splines (Sparse matrix based). R package version 1.3-9-1., https://CRAN.R-project.org/package=cobs.

Ng P, Maechler M (2007). “A Fast and Efficient Implementation of Qualitatively Constrained Quantile Smoothing Splines.” Statistical Modelling, 7(4), 315–328. doi:10.1177/1471082X0700700403.

Corresponding BibTeX entries:

  @Manual{,
    title = {COBS -- Constrained B-splines (Sparse matrix based)},
    author = {Pin T. Ng and Martin Maechler},
    year = {2025},
    note = {R package version 1.3-9-1.},
    url = {https://CRAN.R-project.org/package=cobs},
  }

  @Article{,
    title = {A Fast and Efficient Implementation of Qualitatively
      Constrained Quantile Smoothing Splines},
    author = {Pin Ng and Martin Maechler},
    year = {2007},
    journal = {Statistical Modelling},
    volume = {7},
    number = {4},
    pages = {315--328},
    doi = {10.1177/1471082X0700700403},
  }