To cite groupedSurv in publications, please use:

  Zhiguo Li et al. Efficient estimation of grouped survival models BMC
  Bioinformatics (2019)20:269,
  https://doi.org/10.1186/s12859-019-2899-x

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Efficient estimation of grouped survival models},
    author = {Zhiguo Li and Jiaxing Lin and Alexander B. Sibley and Tracy Truong and Katherina C. Chua and Yu Jiang and Janice McCarthy and Deanna L. Kroetz and Andrew Allen and Kouros Owzar},
    year = {2019},
    journal = {BMC Bioinformatics},
    volume = {20},
    pages = {269},
    doi = {10.1186/s12859-019-2899-x},
    url = {https://doi.org/10.1186/s12859-019-2899-x},
  }