To cite spGARCH in publications use:

Otto, P., Schmid, W. & Garthoff, R. (2018). Generalised spatial and spatiotemporal autoregressive conditional heteroscedasticity Spatial Statistics URL: https://doi.org/10.1016/j.spasta.2018.07.005.

Corresponding BibTeX entry:

  @Article{,
    title = {Generalised spatial and spatiotemporal autoregressive
      conditional heteroscedasticity},
    author = {Philipp Otto and Wolfgang Schmid and Robert Garthoff},
    journal = {Spatial Statistics},
    year = {2018},
    volume = {26},
    pages = {125--145},
    url = {https://doi.org/10.1016/j.spasta.2018.07.005},
  }