nnSVG is described in the following publication:

  Weber et al. (2023), nnSVG for the scalable identification of
  spatially variable genes using nearest-neighbor Gaussian processes,
  bioRxiv.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {nnSVG for the scalable identification of spatially variable genes using nearest-neighbor Gaussian processes},
    author = {Lukas M. Weber and Arkajyoti Saha and Abhirup Datta and Kasper D. Hansen and Stephanie C. Hicks},
    journal = {Nature Communications},
    year = {2023},
    volume = {14},
    number = {4059},
    doi = {https://doi.org/10.1038/s41467-023-39748-z},
  }