To cite scmap in publications use:

  Vladimir Yu. Kiselev, Andrew Yiu, Martin Hemberg (2018): scmap:
  projection of single-cell RNA-seq data across data sets.  Nature
  Methods, URL: https://www.nature.com/articles/nmeth.4644

A BibTeX entry for LaTeX users is

  @Article{,
    title = {scmap: projection of single-cell RNA-seq data across data sets},
    author = {Vladimir Yu. Kiselev and Andrew Yiu and Martin Hemberg},
    year = {2018},
    journal = {Nature Methods},
    url = {https://www.nature.com/articles/nmeth.4644},
  }